diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpClientCodegen.java
index 6049bfa394b3..960202b0bb46 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpClientCodegen.java
@@ -104,6 +104,7 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("ObjectSerializer.mustache", toSrcPath(invokerPackage, srcBasePath), "ObjectSerializer.php"));
         supportingFiles.add(new SupportingFile("ModelInterface.mustache", toSrcPath(modelPackage, srcBasePath), "ModelInterface.php"));
         supportingFiles.add(new SupportingFile("HeaderSelector.mustache", toSrcPath(invokerPackage, srcBasePath), "HeaderSelector.php"));
+        supportingFiles.add(new SupportingFile("DebugPlugin.mustache", toSrcPath(invokerPackage, srcBasePath), "DebugPlugin.php"));
         supportingFiles.add(new SupportingFile("composer.mustache", "", "composer.json"));
         supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
         supportingFiles.add(new SupportingFile("phpunit.xml.mustache", "", "phpunit.xml.dist"));
diff --git a/modules/openapi-generator/src/main/resources/php/ApiException.mustache b/modules/openapi-generator/src/main/resources/php/ApiException.mustache
index dcba96b0e43a..5a96f2f6f5ab 100644
--- a/modules/openapi-generator/src/main/resources/php/ApiException.mustache
+++ b/modules/openapi-generator/src/main/resources/php/ApiException.mustache
@@ -18,7 +18,10 @@
 
 namespace {{invokerPackage}};
 
-use \Exception;
+use Exception;
+use Http\Client\Exception\RequestException;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * ApiException Class Doc Comment
@@ -28,13 +31,13 @@ use \Exception;
  * @author   OpenAPI Generator team
  * @link     https://openapi-generator.tech
  */
-class ApiException extends Exception
+class ApiException extends RequestException
 {
 
     /**
      * The HTTP body of the server response either as Json or string.
      *
-     * @var \stdClass|string|null
+     * @var string|null
      */
     protected $responseBody;
 
@@ -52,19 +55,18 @@ class ApiException extends Exception
      */
     protected $responseObject;
 
-    /**
-     * Constructor
-     *
-     * @param string                $message         Error message
-     * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
-     * @param \stdClass|string|null $responseBody    HTTP decoded body of the server response either as \stdClass or string
-     */
-    public function __construct($message = "", $code = 0, $responseHeaders = [], $responseBody = null)
-    {
-        parent::__construct($message, $code);
-        $this->responseHeaders = $responseHeaders;
-        $this->responseBody = $responseBody;
+    public function __construct(
+        $message,
+        RequestInterface $request,
+        ResponseInterface $response = null,
+        Exception $previous = null
+    ) {
+        parent::__construct($message, $request, $previous);
+        if ($response) {
+            $this->responseHeaders = $response->getHeaders();
+            $this->responseBody = (string) $response->getBody();
+            $this->code = $response->getStatusCode();
+        }
     }
 
     /**
diff --git a/modules/openapi-generator/src/main/resources/php/DebugPlugin.mustache b/modules/openapi-generator/src/main/resources/php/DebugPlugin.mustache
new file mode 100644
index 000000000000..cf256a130411
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/php/DebugPlugin.mustache
@@ -0,0 +1,92 @@
+<?php
+/**
+ * Configuration
+ * PHP version 7.2
+ *
+ * @category Class
+ * @package  {{invokerPackage}}
+ * @author   OpenAPI Generator team
+ * @link     https://openapi-generator.tech
+ */
+
+{{>partial_header}}
+/**
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+namespace {{invokerPackage}};
+
+use Http\Client\Common\Plugin;
+use Http\Promise\Promise;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use function is_resource;
+
+/**
+ * Configuration Class Doc Comment
+ * PHP version 7.2
+ *
+ * @category Class
+ * @package  {{invokerPackage}}
+ * @author   OpenAPI Generator team
+ * @link     https://openapi-generator.tech
+ */
+class DebugPlugin implements Plugin
+{
+
+    /**
+     * @var resource
+     */
+    private $output;
+
+    /**
+     * DebuggingPlugin constructor.
+     *
+     * @param resource $output
+     */
+    public function __construct($output)
+    {
+        if (!is_resource($output)) {
+            throw new \InvalidArgumentException('debugging resource is not valid');
+        }
+        $this->output = $output;
+    }
+
+    public function handleRequest(RequestInterface $request, callable $next, callable $first): Promise
+    {
+        return $next($request)->then(
+            function (ResponseInterface $response) use ($request) {
+                $this->logSuccess($request, $response);
+
+                return $response;
+            },
+            function (ClientExceptionInterface $exception) use ($request) {
+                $this->logError($request, $exception);
+
+                throw $exception;
+            }
+        );
+    }
+
+    private function logSuccess(RequestInterface $request, ResponseInterface $response): void
+    {
+        $methodAndPath = $request->getMethod() . ' ' . $request->getUri()->getPath();
+        $protocol = $response->getProtocolVersion();
+        $responseCode = $response->getStatusCode();
+        \fprintf($this->output, '<%s HTTP/%s> %s', $methodAndPath, $protocol, $responseCode);
+        \fwrite($this->output, "\n");
+    }
+
+    private function logError(RequestInterface $request, ClientExceptionInterface $exception): void
+    {
+        $methodAndPath = $request->getMethod() . ' ' . $request->getUri()->getPath();
+        $protocol = $request->getProtocolVersion();
+        $error = $exception->getMessage();
+        $responseCode = $exception->getCode();
+        \fprintf($this->output, '<%s HTTP/%s> %s %s', $methodAndPath, $responseCode, $error, $protocol);
+        \fwrite($this->output, "\n");
+    }
+}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/php/README.mustache b/modules/openapi-generator/src/main/resources/php/README.mustache
index 544c6fe9d9c6..1d9332375964 100644
--- a/modules/openapi-generator/src/main/resources/php/README.mustache
+++ b/modules/openapi-generator/src/main/resources/php/README.mustache
@@ -34,6 +34,18 @@ To install the bindings via [Composer](https://getcomposer.org/), add the follow
 
 Then run `composer install`
 
+Your project is free to choose the http client of your choice
+Please require packages that will provide http client functionality:
+https://packagist.org/providers/psr/http-client-implementation
+https://packagist.org/providers/php-http/async-client-implementation
+https://packagist.org/providers/psr/http-factory-implementation
+
+As an example:
+
+```
+composer require guzzlehttp/guzzle php-http/guzzle7-adapter http-interop/http-factory-guzzle
+```
+
 ### Manual Installation
 
 Download the files and include `autoload.php`:
@@ -54,8 +66,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 {{#apiInfo}}{{#apis}}{{#-first}}{{#operations}}{{#operation}}{{#-first}}
 {{> php_doc_auth_partial}}
 $apiInstance = new {{invokerPackage}}\Api\{{classname}}(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(){{#hasAuthMethods}},
     $config{{/hasAuthMethods}}
 );
diff --git a/modules/openapi-generator/src/main/resources/php/api.mustache b/modules/openapi-generator/src/main/resources/php/api.mustache
index 206c0a25826a..57f852ee12c1 100644
--- a/modules/openapi-generator/src/main/resources/php/api.mustache
+++ b/modules/openapi-generator/src/main/resources/php/api.mustache
@@ -18,16 +18,32 @@
 
 namespace {{apiPackage}};
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use {{invokerPackage}}\ApiException;
 use {{invokerPackage}}\Configuration;
+use {{invokerPackage}}\DebugPlugin;
 use {{invokerPackage}}\HeaderSelector;
 use {{invokerPackage}}\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * {{classname}} Class Doc Comment
@@ -40,9 +56,19 @@ use {{invokerPackage}}\ObjectSerializer;
 {{#operations}}class {{classname}}
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -60,20 +86,53 @@ use {{invokerPackage}}\ObjectSerializer;
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
+     */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
      */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('{{basePath}}');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -181,32 +240,30 @@ use {{invokerPackage}}\ObjectSerializer;
         $request = $this->{{operationId}}Request({{^vendorExtensions.x-group-parameters}}{{#allParams}}${{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}$associative_array{{/vendorExtensions.x-group-parameters}});
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
+
+            $statusCode = $response->getStatusCode();
             {{#returnType}}
             {{#responses}}
             {{#-first}}
@@ -298,7 +355,7 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function {{operationId}}Async({{^vendorExtensions.x-group-parameters}}{{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}{{{.}}}{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}$associative_array{{/vendorExtensions.x-group-parameters}})
     {
@@ -339,15 +396,14 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function {{operationId}}AsyncWithHttpInfo({{^vendorExtensions.x-group-parameters}}{{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}{{{.}}}{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}$associative_array{{/vendorExtensions.x-group-parameters}})
     {
         $returnType = '{{{returnType}}}';
         $request = $this->{{operationId}}Request({{^vendorExtensions.x-group-parameters}}{{#allParams}}${{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}$associative_array{{/vendorExtensions.x-group-parameters}});
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     {{#returnType}}
@@ -367,7 +423,7 @@ use {{invokerPackage}}\ObjectSerializer;
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                     {{/returnType}}
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -376,9 +432,9 @@ use {{invokerPackage}}\ObjectSerializer;
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -405,7 +461,7 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function {{operationId}}Request({{^vendorExtensions.x-group-parameters}}{{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}{{{.}}}{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}$associative_array{{/vendorExtensions.x-group-parameters}})
     {
@@ -469,7 +525,7 @@ use {{invokerPackage}}\ObjectSerializer;
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         {{#queryParams}}
@@ -564,7 +620,7 @@ use {{invokerPackage}}\ObjectSerializer;
         {{#bodyParams}}
         if (isset(${{paramName}})) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization(${{paramName}}));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization(${{paramName}}));
             } else {
                 $httpBody = ${{paramName}};
             }
@@ -588,11 +644,11 @@ use {{invokerPackage}}\ObjectSerializer;
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -637,41 +693,87 @@ use {{invokerPackage}}\ObjectSerializer;
             $headers
         );
 
+        {{^servers.0}}
+        $operationHost = $this->config->getHost();
+        {{/servers.0}}
         {{#servers.0}}
         $operationHosts = [{{#servers}}"{{{url}}}"{{^-last}}, {{/-last}}{{/servers}}];
         if ($this->hostIndex < 0 || $this->hostIndex >= sizeof($operationHosts)) {
             throw new \InvalidArgumentException("Invalid index {$this->hostIndex} when selecting the host. Must be less than ".sizeof($operationHosts));
         }
         $operationHost = $operationHosts[$this->hostIndex];
-
         {{/servers.0}}
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            '{{httpMethod}}',
-            {{^servers.0}}$this->config->getHost(){{/servers.0}}{{#servers.0}}$operationHost{{/servers.0}} . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('{{httpMethod}}', $uri, $headers, $httpBody);
     }
 
     {{/operation}}
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
 {{/operations}}
diff --git a/modules/openapi-generator/src/main/resources/php/api_doc.mustache b/modules/openapi-generator/src/main/resources/php/api_doc.mustache
index 2fc255126f7c..3a794f7e5b4e 100644
--- a/modules/openapi-generator/src/main/resources/php/api_doc.mustache
+++ b/modules/openapi-generator/src/main/resources/php/api_doc.mustache
@@ -27,8 +27,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 {{> php_doc_auth_partial}}
 $apiInstance = new {{invokerPackage}}\Api\{{classname}}(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(){{#hasAuthMethods}},
     $config{{/hasAuthMethods}}
 );
diff --git a/modules/openapi-generator/src/main/resources/php/composer.mustache b/modules/openapi-generator/src/main/resources/php/composer.mustache
index 265bd713d521..7ef3e16b0e81 100644
--- a/modules/openapi-generator/src/main/resources/php/composer.mustache
+++ b/modules/openapi-generator/src/main/resources/php/composer.mustache
@@ -21,16 +21,29 @@
             "homepage": "https://openapi-generator.tech"
         }
     ],
+    "config": {
+        "sort-packages": true
+    },
     "require": {
         "php": ">=7.2",
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/psr7": "^1.8 || ^2.0",
+        "php-http/async-client-implementation": "^1.0",
+        "php-http/client-common": "^2.4",
+        "php-http/discovery": "^1.14",
+        "php-http/httplug": "^2.2",
+        "psr/http-client-implementation": "^1.0",
+        "psr/http-factory": "^1.0",
+        "psr/http-factory-implementation": "^1.0",
+        "psr/http-message": "^1.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^8.0 || ^9.0",
-        "friendsofphp/php-cs-fixer": "^2.12"
+        "friendsofphp/php-cs-fixer": "^2.12",
+        "guzzlehttp/guzzle": "^7.0",
+        "php-http/guzzle7-adapter": "^1.0"
     },
     "autoload": {
         "psr-4": { "{{escapedInvokerPackage}}\\" : "{{srcBasePath}}/" }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/.openapi-generator/FILES b/samples/client/petstore/php/OpenAPIClient-php/.openapi-generator/FILES
index fda1dc9138c5..898026ae3cfe 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/.openapi-generator/FILES
+++ b/samples/client/petstore/php/OpenAPIClient-php/.openapi-generator/FILES
@@ -64,6 +64,7 @@ lib/Api/StoreApi.php
 lib/Api/UserApi.php
 lib/ApiException.php
 lib/Configuration.php
+lib/DebugPlugin.php
 lib/HeaderSelector.php
 lib/Model/AdditionalPropertiesClass.php
 lib/Model/Animal.php
diff --git a/samples/client/petstore/php/OpenAPIClient-php/README.md b/samples/client/petstore/php/OpenAPIClient-php/README.md
index 2f4807ddee0b..e3fc61140c1b 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/README.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/README.md
@@ -29,6 +29,18 @@ To install the bindings via [Composer](https://getcomposer.org/), add the follow
 
 Then run `composer install`
 
+Your project is free to choose the http client of your choice
+Please require packages that will provide http client functionality:
+https://packagist.org/providers/psr/http-client-implementation
+https://packagist.org/providers/php-http/async-client-implementation
+https://packagist.org/providers/psr/http-factory-implementation
+
+As an example:
+
+```
+composer require guzzlehttp/guzzle php-http/guzzle7-adapter http-interop/http-factory-guzzle
+```
+
 ### Manual Installation
 
 Download the files and include `autoload.php`:
@@ -50,8 +62,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\AnotherFakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $client = new \OpenAPI\Client\Model\Client(); // \OpenAPI\Client\Model\Client | client model
diff --git a/samples/client/petstore/php/OpenAPIClient-php/composer.json b/samples/client/petstore/php/OpenAPIClient-php/composer.json
index 08efaa27b921..988cf821ed56 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/composer.json
+++ b/samples/client/petstore/php/OpenAPIClient-php/composer.json
@@ -18,16 +18,29 @@
             "homepage": "https://openapi-generator.tech"
         }
     ],
+    "config": {
+        "sort-packages": true
+    },
     "require": {
         "php": ">=7.2",
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/psr7": "^1.8 || ^2.0",
+        "php-http/async-client-implementation": "^1.0",
+        "php-http/client-common": "^2.4",
+        "php-http/discovery": "^1.14",
+        "php-http/httplug": "^2.2",
+        "psr/http-client-implementation": "^1.0",
+        "psr/http-factory": "^1.0",
+        "psr/http-factory-implementation": "^1.0",
+        "psr/http-message": "^1.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^8.0 || ^9.0",
-        "friendsofphp/php-cs-fixer": "^2.12"
+        "friendsofphp/php-cs-fixer": "^2.12",
+        "guzzlehttp/guzzle": "^7.0",
+        "php-http/guzzle7-adapter": "^1.0"
     },
     "autoload": {
         "psr-4": { "OpenAPI\\Client\\" : "lib/" }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/AnotherFakeApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/AnotherFakeApi.md
index 20ee44a4bf0c..42a2243039b7 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/AnotherFakeApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/AnotherFakeApi.md
@@ -26,8 +26,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\AnotherFakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $client = new \OpenAPI\Client\Model\Client(); // \OpenAPI\Client\Model\Client | client model
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/DefaultApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/DefaultApi.md
index 020bf4d8fb88..2b9d3bd5bc31 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/DefaultApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/DefaultApi.md
@@ -24,8 +24,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\DefaultApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeApi.md
index 4319d48a4083..ff9d290419b2 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeApi.md
@@ -39,8 +39,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 
@@ -91,8 +91,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -151,8 +151,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $body = True; // bool | Input boolean as post body
@@ -207,8 +207,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $outer_composite = new \OpenAPI\Client\Model\OuterComposite(); // \OpenAPI\Client\Model\OuterComposite | Input composite as post body
@@ -263,8 +263,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $body = 3.4; // float | Input number as post body
@@ -319,8 +319,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $body = 'body_example'; // string | Input string as post body
@@ -375,8 +375,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $outer_object_with_enum_property = new \OpenAPI\Client\Model\OuterObjectWithEnumProperty(); // \OpenAPI\Client\Model\OuterObjectWithEnumProperty | Input enum (int) as post body
@@ -431,8 +431,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $file_schema_test_class = new \OpenAPI\Client\Model\FileSchemaTestClass(); // \OpenAPI\Client\Model\FileSchemaTestClass
@@ -484,8 +484,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $query = 'query_example'; // string
@@ -541,8 +541,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $client = new \OpenAPI\Client\Model\Client(); // \OpenAPI\Client\Model\Client | client model
@@ -602,8 +602,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -684,8 +684,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $enum_header_string_array = array('enum_header_string_array_example'); // string[] | Header parameter enum test (string array)
@@ -756,8 +756,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -822,8 +822,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $request_body = array('key' => 'request_body_example'); // array<string,string> | request body
@@ -875,8 +875,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $param = 'param_example'; // string | field1
@@ -932,8 +932,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $pipe = array('pipe_example'); // string[]
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeClassnameTags123Api.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeClassnameTags123Api.md
index 58088ff9def6..48b2139c35f1 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeClassnameTags123Api.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/FakeClassnameTags123Api.md
@@ -31,8 +31,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setApiKey('ap
 
 
 $apiInstance = new OpenAPI\Client\Api\FakeClassnameTags123Api(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/PetApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/PetApi.md
index 079f8c03a356..bc994e8179c8 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/PetApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/PetApi.md
@@ -35,8 +35,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -92,8 +92,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -153,8 +153,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -213,8 +213,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -275,8 +275,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setApiKey('ap
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -333,8 +333,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -390,8 +390,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -451,8 +451,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -513,8 +513,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setAccessToke
 
 
 $apiInstance = new OpenAPI\Client\Api\PetApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/StoreApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/StoreApi.md
index 7d13c3497f30..ab2e4b7ae41b 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/StoreApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/StoreApi.md
@@ -29,8 +29,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\StoreApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $order_id = 'order_id_example'; // string | ID of the order that needs to be deleted
@@ -89,8 +89,8 @@ $config = OpenAPI\Client\Configuration::getDefaultConfiguration()->setApiKey('ap
 
 
 $apiInstance = new OpenAPI\Client\Api\StoreApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client(),
     $config
 );
@@ -143,8 +143,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\StoreApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $order_id = 56; // int | ID of pet that needs to be fetched
@@ -197,8 +197,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\StoreApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $order = new \OpenAPI\Client\Model\Order(); // \OpenAPI\Client\Model\Order | order placed for purchasing the pet
diff --git a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/UserApi.md b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/UserApi.md
index 04fb1b76378a..97aaf92797c7 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/docs/Api/UserApi.md
+++ b/samples/client/petstore/php/OpenAPIClient-php/docs/Api/UserApi.md
@@ -33,8 +33,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $user = new \OpenAPI\Client\Model\User(); // \OpenAPI\Client\Model\User | Created user object
@@ -86,8 +86,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $user = array(new \OpenAPI\Client\Model\User()); // \OpenAPI\Client\Model\User[] | List of user object
@@ -139,8 +139,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $user = array(new \OpenAPI\Client\Model\User()); // \OpenAPI\Client\Model\User[] | List of user object
@@ -194,8 +194,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $username = 'username_example'; // string | The name that needs to be deleted
@@ -247,8 +247,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $username = 'username_example'; // string | The name that needs to be fetched. Use user1 for testing.
@@ -301,8 +301,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $username = 'username_example'; // string | The user name for login
@@ -357,8 +357,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 
@@ -409,8 +409,8 @@ require_once(__DIR__ . '/vendor/autoload.php');
 
 
 $apiInstance = new OpenAPI\Client\Api\UserApi(
-    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
-    // This is optional, `GuzzleHttp\Client` will be used as default.
+    // If you want use custom http client, pass your client which implements `Psr\Http\Client\ClientInterface`.
+    // This is optional, `Psr18ClientDiscovery` will be used to find http client. For instance `GuzzleHttp\Client` implements that interface
     new GuzzleHttp\Client()
 );
 $username = 'username_example'; // string | name that need to be deleted
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/AnotherFakeApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/AnotherFakeApi.php
index e274c49defda..b81a7fa52cde 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/AnotherFakeApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/AnotherFakeApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * AnotherFakeApi Class Doc Comment
@@ -49,9 +65,19 @@
 class AnotherFakeApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class AnotherFakeApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
+     */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
      */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -147,33 +206,31 @@ public function call123TestSpecialTagsWithHttpInfo($client)
         $request = $this->call123TestSpecialTagsRequest($client);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Client' === '\SplFileObject') {
@@ -225,7 +282,7 @@ public function call123TestSpecialTagsWithHttpInfo($client)
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function call123TestSpecialTagsAsync($client)
     {
@@ -245,15 +302,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function call123TestSpecialTagsAsyncWithHttpInfo($client)
     {
         $returnType = '\OpenAPI\Client\Model\Client';
         $request = $this->call123TestSpecialTagsRequest($client);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -268,7 +324,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -277,9 +333,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -291,7 +347,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function call123TestSpecialTagsRequest($client)
     {
@@ -306,7 +362,7 @@ public function call123TestSpecialTagsRequest($client)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -327,7 +383,7 @@ public function call123TestSpecialTagsRequest($client)
         // for model (json/xml)
         if (isset($client)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($client));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($client));
             } else {
                 $httpBody = $client;
             }
@@ -347,11 +403,11 @@ public function call123TestSpecialTagsRequest($client)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -367,31 +423,76 @@ public function call123TestSpecialTagsRequest($client)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PATCH',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PATCH', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/DefaultApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/DefaultApi.php
index c34fe66e69ee..66408ef9bab9 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/DefaultApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/DefaultApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * DefaultApi Class Doc Comment
@@ -49,9 +65,19 @@
 class DefaultApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class DefaultApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
+     */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
      */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -141,33 +200,31 @@ public function fooGetWithHttpInfo()
         $request = $this->fooGetRequest();
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 default:
                     if ('\OpenAPI\Client\Model\InlineResponseDefault' === '\SplFileObject') {
@@ -216,7 +273,7 @@ public function fooGetWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fooGetAsync()
     {
@@ -233,15 +290,14 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fooGetAsyncWithHttpInfo()
     {
         $returnType = '\OpenAPI\Client\Model\InlineResponseDefault';
         $request = $this->fooGetRequest();
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -256,7 +312,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -265,9 +321,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -278,7 +334,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fooGetRequest()
     {
@@ -287,7 +343,7 @@ public function fooGetRequest()
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -322,11 +378,11 @@ public function fooGetRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -342,31 +398,76 @@ public function fooGetRequest()
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeApi.php
index a9b246949f7d..f1006bcae18b 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * FakeApi Class Doc Comment
@@ -49,9 +65,19 @@
 class FakeApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class FakeApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
      */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
+     */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -145,33 +204,31 @@ public function fakeHealthGetWithHttpInfo()
         $request = $this->fakeHealthGetRequest();
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\HealthCheckResult' === '\SplFileObject') {
@@ -222,7 +279,7 @@ public function fakeHealthGetWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeHealthGetAsync()
     {
@@ -241,15 +298,14 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeHealthGetAsyncWithHttpInfo()
     {
         $returnType = '\OpenAPI\Client\Model\HealthCheckResult';
         $request = $this->fakeHealthGetRequest();
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -264,7 +320,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -273,9 +329,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -286,7 +342,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeHealthGetRequest()
     {
@@ -295,7 +351,7 @@ public function fakeHealthGetRequest()
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -330,11 +386,11 @@ public function fakeHealthGetRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -350,13 +406,11 @@ public function fakeHealthGetRequest()
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -395,33 +449,31 @@ public function fakeHttpSignatureTestWithHttpInfo($pet, $query_1 = null, $header
         $request = $this->fakeHttpSignatureTestRequest($pet, $query_1, $header_1);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -441,7 +493,7 @@ public function fakeHttpSignatureTestWithHttpInfo($pet, $query_1 = null, $header
      * @param  string $header_1 header parameter (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeHttpSignatureTestAsync($pet, $query_1 = null, $header_1 = null)
     {
@@ -463,20 +515,19 @@ function ($response) {
      * @param  string $header_1 header parameter (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeHttpSignatureTestAsyncWithHttpInfo($pet, $query_1 = null, $header_1 = null)
     {
         $returnType = '';
         $request = $this->fakeHttpSignatureTestRequest($pet, $query_1, $header_1);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -485,9 +536,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -501,7 +552,7 @@ function ($exception) {
      * @param  string $header_1 header parameter (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeHttpSignatureTestRequest($pet, $query_1 = null, $header_1 = null)
     {
@@ -516,7 +567,7 @@ public function fakeHttpSignatureTestRequest($pet, $query_1 = null, $header_1 =
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -552,7 +603,7 @@ public function fakeHttpSignatureTestRequest($pet, $query_1 = null, $header_1 =
         // for model (json/xml)
         if (isset($pet)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($pet));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($pet));
             } else {
                 $httpBody = $pet;
             }
@@ -572,11 +623,11 @@ public function fakeHttpSignatureTestRequest($pet, $query_1 = null, $header_1 =
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -592,13 +643,11 @@ public function fakeHttpSignatureTestRequest($pet, $query_1 = null, $header_1 =
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -630,33 +679,31 @@ public function fakeOuterBooleanSerializeWithHttpInfo($body = null)
         $request = $this->fakeOuterBooleanSerializeRequest($body);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('bool' === '\SplFileObject') {
@@ -706,7 +753,7 @@ public function fakeOuterBooleanSerializeWithHttpInfo($body = null)
      * @param  bool $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterBooleanSerializeAsync($body = null)
     {
@@ -724,15 +771,14 @@ function ($response) {
      * @param  bool $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterBooleanSerializeAsyncWithHttpInfo($body = null)
     {
         $returnType = 'bool';
         $request = $this->fakeOuterBooleanSerializeRequest($body);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -747,7 +793,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -756,9 +802,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -770,7 +816,7 @@ function ($exception) {
      * @param  bool $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeOuterBooleanSerializeRequest($body = null)
     {
@@ -779,7 +825,7 @@ public function fakeOuterBooleanSerializeRequest($body = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -800,7 +846,7 @@ public function fakeOuterBooleanSerializeRequest($body = null)
         // for model (json/xml)
         if (isset($body)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($body));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($body));
             } else {
                 $httpBody = $body;
             }
@@ -820,11 +866,11 @@ public function fakeOuterBooleanSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -840,13 +886,11 @@ public function fakeOuterBooleanSerializeRequest($body = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -878,33 +922,31 @@ public function fakeOuterCompositeSerializeWithHttpInfo($outer_composite = null)
         $request = $this->fakeOuterCompositeSerializeRequest($outer_composite);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\OuterComposite' === '\SplFileObject') {
@@ -954,7 +996,7 @@ public function fakeOuterCompositeSerializeWithHttpInfo($outer_composite = null)
      * @param  \OpenAPI\Client\Model\OuterComposite $outer_composite Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterCompositeSerializeAsync($outer_composite = null)
     {
@@ -972,15 +1014,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\OuterComposite $outer_composite Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterCompositeSerializeAsyncWithHttpInfo($outer_composite = null)
     {
         $returnType = '\OpenAPI\Client\Model\OuterComposite';
         $request = $this->fakeOuterCompositeSerializeRequest($outer_composite);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -995,7 +1036,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1004,9 +1045,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1018,7 +1059,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\OuterComposite $outer_composite Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeOuterCompositeSerializeRequest($outer_composite = null)
     {
@@ -1027,7 +1068,7 @@ public function fakeOuterCompositeSerializeRequest($outer_composite = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1048,7 +1089,7 @@ public function fakeOuterCompositeSerializeRequest($outer_composite = null)
         // for model (json/xml)
         if (isset($outer_composite)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($outer_composite));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($outer_composite));
             } else {
                 $httpBody = $outer_composite;
             }
@@ -1068,11 +1109,11 @@ public function fakeOuterCompositeSerializeRequest($outer_composite = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1088,13 +1129,11 @@ public function fakeOuterCompositeSerializeRequest($outer_composite = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1126,33 +1165,31 @@ public function fakeOuterNumberSerializeWithHttpInfo($body = null)
         $request = $this->fakeOuterNumberSerializeRequest($body);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('float' === '\SplFileObject') {
@@ -1202,7 +1239,7 @@ public function fakeOuterNumberSerializeWithHttpInfo($body = null)
      * @param  float $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterNumberSerializeAsync($body = null)
     {
@@ -1220,15 +1257,14 @@ function ($response) {
      * @param  float $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterNumberSerializeAsyncWithHttpInfo($body = null)
     {
         $returnType = 'float';
         $request = $this->fakeOuterNumberSerializeRequest($body);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1243,7 +1279,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1252,9 +1288,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1266,7 +1302,7 @@ function ($exception) {
      * @param  float $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeOuterNumberSerializeRequest($body = null)
     {
@@ -1275,7 +1311,7 @@ public function fakeOuterNumberSerializeRequest($body = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1296,7 +1332,7 @@ public function fakeOuterNumberSerializeRequest($body = null)
         // for model (json/xml)
         if (isset($body)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($body));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($body));
             } else {
                 $httpBody = $body;
             }
@@ -1316,11 +1352,11 @@ public function fakeOuterNumberSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1336,13 +1372,11 @@ public function fakeOuterNumberSerializeRequest($body = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1374,33 +1408,31 @@ public function fakeOuterStringSerializeWithHttpInfo($body = null)
         $request = $this->fakeOuterStringSerializeRequest($body);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('string' === '\SplFileObject') {
@@ -1450,7 +1482,7 @@ public function fakeOuterStringSerializeWithHttpInfo($body = null)
      * @param  string $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterStringSerializeAsync($body = null)
     {
@@ -1468,15 +1500,14 @@ function ($response) {
      * @param  string $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakeOuterStringSerializeAsyncWithHttpInfo($body = null)
     {
         $returnType = 'string';
         $request = $this->fakeOuterStringSerializeRequest($body);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1491,7 +1522,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1500,9 +1531,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1514,7 +1545,7 @@ function ($exception) {
      * @param  string $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakeOuterStringSerializeRequest($body = null)
     {
@@ -1523,7 +1554,7 @@ public function fakeOuterStringSerializeRequest($body = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1544,7 +1575,7 @@ public function fakeOuterStringSerializeRequest($body = null)
         // for model (json/xml)
         if (isset($body)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($body));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($body));
             } else {
                 $httpBody = $body;
             }
@@ -1564,11 +1595,11 @@ public function fakeOuterStringSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1584,13 +1615,11 @@ public function fakeOuterStringSerializeRequest($body = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1622,33 +1651,31 @@ public function fakePropertyEnumIntegerSerializeWithHttpInfo($outer_object_with_
         $request = $this->fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_property);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\OuterObjectWithEnumProperty' === '\SplFileObject') {
@@ -1698,7 +1725,7 @@ public function fakePropertyEnumIntegerSerializeWithHttpInfo($outer_object_with_
      * @param  \OpenAPI\Client\Model\OuterObjectWithEnumProperty $outer_object_with_enum_property Input enum (int) as post body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakePropertyEnumIntegerSerializeAsync($outer_object_with_enum_property)
     {
@@ -1716,15 +1743,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\OuterObjectWithEnumProperty $outer_object_with_enum_property Input enum (int) as post body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function fakePropertyEnumIntegerSerializeAsyncWithHttpInfo($outer_object_with_enum_property)
     {
         $returnType = '\OpenAPI\Client\Model\OuterObjectWithEnumProperty';
         $request = $this->fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_property);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1739,7 +1765,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1748,9 +1774,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1762,7 +1788,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\OuterObjectWithEnumProperty $outer_object_with_enum_property Input enum (int) as post body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_property)
     {
@@ -1777,7 +1803,7 @@ public function fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1798,7 +1824,7 @@ public function fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_
         // for model (json/xml)
         if (isset($outer_object_with_enum_property)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($outer_object_with_enum_property));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($outer_object_with_enum_property));
             } else {
                 $httpBody = $outer_object_with_enum_property;
             }
@@ -1818,11 +1844,11 @@ public function fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1838,13 +1864,11 @@ public function fakePropertyEnumIntegerSerializeRequest($outer_object_with_enum_
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1875,33 +1899,31 @@ public function testBodyWithFileSchemaWithHttpInfo($file_schema_test_class)
         $request = $this->testBodyWithFileSchemaRequest($file_schema_test_class);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -1917,7 +1939,7 @@ public function testBodyWithFileSchemaWithHttpInfo($file_schema_test_class)
      * @param  \OpenAPI\Client\Model\FileSchemaTestClass $file_schema_test_class (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testBodyWithFileSchemaAsync($file_schema_test_class)
     {
@@ -1935,20 +1957,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\FileSchemaTestClass $file_schema_test_class (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testBodyWithFileSchemaAsyncWithHttpInfo($file_schema_test_class)
     {
         $returnType = '';
         $request = $this->testBodyWithFileSchemaRequest($file_schema_test_class);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1957,9 +1978,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1971,7 +1992,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\FileSchemaTestClass $file_schema_test_class (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testBodyWithFileSchemaRequest($file_schema_test_class)
     {
@@ -1986,7 +2007,7 @@ public function testBodyWithFileSchemaRequest($file_schema_test_class)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -2007,7 +2028,7 @@ public function testBodyWithFileSchemaRequest($file_schema_test_class)
         // for model (json/xml)
         if (isset($file_schema_test_class)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($file_schema_test_class));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($file_schema_test_class));
             } else {
                 $httpBody = $file_schema_test_class;
             }
@@ -2027,11 +2048,11 @@ public function testBodyWithFileSchemaRequest($file_schema_test_class)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2047,13 +2068,11 @@ public function testBodyWithFileSchemaRequest($file_schema_test_class)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PUT',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PUT', $uri, $headers, $httpBody);
     }
 
     /**
@@ -2086,33 +2105,31 @@ public function testBodyWithQueryParamsWithHttpInfo($query, $user)
         $request = $this->testBodyWithQueryParamsRequest($query, $user);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -2129,7 +2146,7 @@ public function testBodyWithQueryParamsWithHttpInfo($query, $user)
      * @param  \OpenAPI\Client\Model\User $user (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testBodyWithQueryParamsAsync($query, $user)
     {
@@ -2148,20 +2165,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\User $user (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testBodyWithQueryParamsAsyncWithHttpInfo($query, $user)
     {
         $returnType = '';
         $request = $this->testBodyWithQueryParamsRequest($query, $user);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -2170,9 +2186,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -2185,7 +2201,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\User $user (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testBodyWithQueryParamsRequest($query, $user)
     {
@@ -2206,7 +2222,7 @@ public function testBodyWithQueryParamsRequest($query, $user)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -2238,7 +2254,7 @@ public function testBodyWithQueryParamsRequest($query, $user)
         // for model (json/xml)
         if (isset($user)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($user));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($user));
             } else {
                 $httpBody = $user;
             }
@@ -2258,11 +2274,11 @@ public function testBodyWithQueryParamsRequest($query, $user)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2278,13 +2294,11 @@ public function testBodyWithQueryParamsRequest($query, $user)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PUT',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PUT', $uri, $headers, $httpBody);
     }
 
     /**
@@ -2320,33 +2334,31 @@ public function testClientModelWithHttpInfo($client)
         $request = $this->testClientModelRequest($client);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Client' === '\SplFileObject') {
@@ -2398,7 +2410,7 @@ public function testClientModelWithHttpInfo($client)
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testClientModelAsync($client)
     {
@@ -2418,15 +2430,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testClientModelAsyncWithHttpInfo($client)
     {
         $returnType = '\OpenAPI\Client\Model\Client';
         $request = $this->testClientModelRequest($client);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -2441,7 +2452,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -2450,9 +2461,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -2464,7 +2475,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testClientModelRequest($client)
     {
@@ -2479,7 +2490,7 @@ public function testClientModelRequest($client)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -2500,7 +2511,7 @@ public function testClientModelRequest($client)
         // for model (json/xml)
         if (isset($client)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($client));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($client));
             } else {
                 $httpBody = $client;
             }
@@ -2520,11 +2531,11 @@ public function testClientModelRequest($client)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2540,13 +2551,11 @@ public function testClientModelRequest($client)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PATCH',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PATCH', $uri, $headers, $httpBody);
     }
 
     /**
@@ -2607,33 +2616,31 @@ public function testEndpointParametersWithHttpInfo($number, $double, $pattern_wi
         $request = $this->testEndpointParametersRequest($number, $double, $pattern_without_delimiter, $byte, $integer, $int32, $int64, $float, $string, $binary, $date, $date_time, $password, $callback);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -2664,7 +2671,7 @@ public function testEndpointParametersWithHttpInfo($number, $double, $pattern_wi
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testEndpointParametersAsync($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
     {
@@ -2697,20 +2704,19 @@ function ($response) {
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testEndpointParametersAsyncWithHttpInfo($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
     {
         $returnType = '';
         $request = $this->testEndpointParametersRequest($number, $double, $pattern_without_delimiter, $byte, $integer, $int32, $int64, $float, $string, $binary, $date, $date_time, $password, $callback);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -2719,9 +2725,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -2746,7 +2752,7 @@ function ($exception) {
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testEndpointParametersRequest($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
     {
@@ -2826,7 +2832,7 @@ public function testEndpointParametersRequest($number, $double, $pattern_without
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -2925,11 +2931,11 @@ public function testEndpointParametersRequest($number, $double, $pattern_without
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2949,13 +2955,11 @@ public function testEndpointParametersRequest($number, $double, $pattern_without
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -3004,33 +3008,31 @@ public function testEnumParametersWithHttpInfo($enum_header_string_array = null,
         $request = $this->testEnumParametersRequest($enum_header_string_array, $enum_header_string, $enum_query_string_array, $enum_query_string, $enum_query_integer, $enum_query_double, $enum_form_string_array, $enum_form_string);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -3055,7 +3057,7 @@ public function testEnumParametersWithHttpInfo($enum_header_string_array = null,
      * @param  string $enum_form_string Form parameter enum test (string) (optional, default to '-efg')
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testEnumParametersAsync($enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null, $enum_form_string_array = '$', $enum_form_string = '-efg')
     {
@@ -3082,20 +3084,19 @@ function ($response) {
      * @param  string $enum_form_string Form parameter enum test (string) (optional, default to '-efg')
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testEnumParametersAsyncWithHttpInfo($enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null, $enum_form_string_array = '$', $enum_form_string = '-efg')
     {
         $returnType = '';
         $request = $this->testEnumParametersRequest($enum_header_string_array, $enum_header_string, $enum_query_string_array, $enum_query_string, $enum_query_integer, $enum_query_double, $enum_form_string_array, $enum_form_string);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -3104,9 +3105,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -3125,7 +3126,7 @@ function ($exception) {
      * @param  string $enum_form_string Form parameter enum test (string) (optional, default to '-efg')
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testEnumParametersRequest($enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null, $enum_form_string_array = '$', $enum_form_string = '-efg')
     {
@@ -3134,7 +3135,7 @@ public function testEnumParametersRequest($enum_header_string_array = null, $enu
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -3232,11 +3233,11 @@ public function testEnumParametersRequest($enum_header_string_array = null, $enu
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -3252,13 +3253,11 @@ public function testEnumParametersRequest($enum_header_string_array = null, $enu
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -3307,33 +3306,31 @@ public function testGroupParametersWithHttpInfo($associative_array)
         $request = $this->testGroupParametersRequest($associative_array);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -3358,7 +3355,7 @@ public function testGroupParametersWithHttpInfo($associative_array)
      * @param  int $int64_group Integer in group parameters (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testGroupParametersAsync($associative_array)
     {
@@ -3385,20 +3382,19 @@ function ($response) {
      * @param  int $int64_group Integer in group parameters (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testGroupParametersAsyncWithHttpInfo($associative_array)
     {
         $returnType = '';
         $request = $this->testGroupParametersRequest($associative_array);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -3407,9 +3403,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -3428,7 +3424,7 @@ function ($exception) {
      * @param  int $int64_group Integer in group parameters (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testGroupParametersRequest($associative_array)
     {
@@ -3463,7 +3459,7 @@ public function testGroupParametersRequest($associative_array)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -3550,11 +3546,11 @@ public function testGroupParametersRequest($associative_array)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -3574,13 +3570,11 @@ public function testGroupParametersRequest($associative_array)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'DELETE',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('DELETE', $uri, $headers, $httpBody);
     }
 
     /**
@@ -3615,33 +3609,31 @@ public function testInlineAdditionalPropertiesWithHttpInfo($request_body)
         $request = $this->testInlineAdditionalPropertiesRequest($request_body);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -3659,7 +3651,7 @@ public function testInlineAdditionalPropertiesWithHttpInfo($request_body)
      * @param  array<string,string> $request_body request body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testInlineAdditionalPropertiesAsync($request_body)
     {
@@ -3679,20 +3671,19 @@ function ($response) {
      * @param  array<string,string> $request_body request body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testInlineAdditionalPropertiesAsyncWithHttpInfo($request_body)
     {
         $returnType = '';
         $request = $this->testInlineAdditionalPropertiesRequest($request_body);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -3701,9 +3692,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -3715,7 +3706,7 @@ function ($exception) {
      * @param  array<string,string> $request_body request body (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testInlineAdditionalPropertiesRequest($request_body)
     {
@@ -3730,7 +3721,7 @@ public function testInlineAdditionalPropertiesRequest($request_body)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -3751,7 +3742,7 @@ public function testInlineAdditionalPropertiesRequest($request_body)
         // for model (json/xml)
         if (isset($request_body)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($request_body));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($request_body));
             } else {
                 $httpBody = $request_body;
             }
@@ -3771,11 +3762,11 @@ public function testInlineAdditionalPropertiesRequest($request_body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -3791,13 +3782,11 @@ public function testInlineAdditionalPropertiesRequest($request_body)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -3834,33 +3823,31 @@ public function testJsonFormDataWithHttpInfo($param, $param2)
         $request = $this->testJsonFormDataRequest($param, $param2);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -3879,7 +3866,7 @@ public function testJsonFormDataWithHttpInfo($param, $param2)
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testJsonFormDataAsync($param, $param2)
     {
@@ -3900,20 +3887,19 @@ function ($response) {
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testJsonFormDataAsyncWithHttpInfo($param, $param2)
     {
         $returnType = '';
         $request = $this->testJsonFormDataRequest($param, $param2);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -3922,9 +3908,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -3937,7 +3923,7 @@ function ($exception) {
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testJsonFormDataRequest($param, $param2)
     {
@@ -3958,7 +3944,7 @@ public function testJsonFormDataRequest($param, $param2)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -4001,11 +3987,11 @@ public function testJsonFormDataRequest($param, $param2)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -4021,13 +4007,11 @@ public function testJsonFormDataRequest($param, $param2)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -4066,33 +4050,31 @@ public function testQueryParameterCollectionFormatWithHttpInfo($pipe, $ioutil, $
         $request = $this->testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http, $url, $context);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -4112,7 +4094,7 @@ public function testQueryParameterCollectionFormatWithHttpInfo($pipe, $ioutil, $
      * @param  string[] $context (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testQueryParameterCollectionFormatAsync($pipe, $ioutil, $http, $url, $context)
     {
@@ -4134,20 +4116,19 @@ function ($response) {
      * @param  string[] $context (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testQueryParameterCollectionFormatAsyncWithHttpInfo($pipe, $ioutil, $http, $url, $context)
     {
         $returnType = '';
         $request = $this->testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http, $url, $context);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -4156,9 +4137,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -4174,7 +4155,7 @@ function ($exception) {
      * @param  string[] $context (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http, $url, $context)
     {
@@ -4213,7 +4194,7 @@ public function testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http,
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -4291,11 +4272,11 @@ public function testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http,
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -4311,31 +4292,76 @@ public function testQueryParameterCollectionFormatRequest($pipe, $ioutil, $http,
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PUT',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PUT', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeClassnameTags123Api.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeClassnameTags123Api.php
index 3a839b441951..43a4fdeb1222 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeClassnameTags123Api.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/FakeClassnameTags123Api.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * FakeClassnameTags123Api Class Doc Comment
@@ -49,9 +65,19 @@
 class FakeClassnameTags123Api
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class FakeClassnameTags123Api
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
+     */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
      */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -147,33 +206,31 @@ public function testClassnameWithHttpInfo($client)
         $request = $this->testClassnameRequest($client);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Client' === '\SplFileObject') {
@@ -225,7 +282,7 @@ public function testClassnameWithHttpInfo($client)
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testClassnameAsync($client)
     {
@@ -245,15 +302,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function testClassnameAsyncWithHttpInfo($client)
     {
         $returnType = '\OpenAPI\Client\Model\Client';
         $request = $this->testClassnameRequest($client);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -268,7 +324,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -277,9 +333,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -291,7 +347,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Client $client client model (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function testClassnameRequest($client)
     {
@@ -306,7 +362,7 @@ public function testClassnameRequest($client)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -327,7 +383,7 @@ public function testClassnameRequest($client)
         // for model (json/xml)
         if (isset($client)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($client));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($client));
             } else {
                 $httpBody = $client;
             }
@@ -347,11 +403,11 @@ public function testClassnameRequest($client)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -372,31 +428,76 @@ public function testClassnameRequest($client)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PATCH',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PATCH', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/PetApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/PetApi.php
index 20a126194bc7..7a4b97d1cd38 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/PetApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/PetApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * PetApi Class Doc Comment
@@ -49,9 +65,19 @@
 class PetApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class PetApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
      */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
+     */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -154,33 +213,31 @@ public function addPetWithHttpInfo($pet)
         $request = $this->addPetRequest($pet);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -202,7 +259,7 @@ public function addPetWithHttpInfo($pet)
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function addPetAsync($pet)
     {
@@ -226,20 +283,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function addPetAsyncWithHttpInfo($pet)
     {
         $returnType = '';
         $request = $this->addPetRequest($pet);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -248,9 +304,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -266,7 +322,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function addPetRequest($pet)
     {
@@ -281,7 +337,7 @@ public function addPetRequest($pet)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -302,7 +358,7 @@ public function addPetRequest($pet)
         // for model (json/xml)
         if (isset($pet)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($pet));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($pet));
             } else {
                 $httpBody = $pet;
             }
@@ -322,11 +378,11 @@ public function addPetRequest($pet)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -352,13 +408,9 @@ public function addPetRequest($pet)
         }
         $operationHost = $operationHosts[$this->hostIndex];
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $operationHost . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -395,33 +447,31 @@ public function deletePetWithHttpInfo($pet_id, $api_key = null)
         $request = $this->deletePetRequest($pet_id, $api_key);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -440,7 +490,7 @@ public function deletePetWithHttpInfo($pet_id, $api_key = null)
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deletePetAsync($pet_id, $api_key = null)
     {
@@ -461,20 +511,19 @@ function ($response) {
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deletePetAsyncWithHttpInfo($pet_id, $api_key = null)
     {
         $returnType = '';
         $request = $this->deletePetRequest($pet_id, $api_key);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -483,9 +532,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -498,7 +547,7 @@ function ($exception) {
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function deletePetRequest($pet_id, $api_key = null)
     {
@@ -513,7 +562,7 @@ public function deletePetRequest($pet_id, $api_key = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -560,11 +609,11 @@ public function deletePetRequest($pet_id, $api_key = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -584,13 +633,11 @@ public function deletePetRequest($pet_id, $api_key = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'DELETE',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('DELETE', $uri, $headers, $httpBody);
     }
 
     /**
@@ -626,33 +673,31 @@ public function findPetsByStatusWithHttpInfo($status)
         $request = $this->findPetsByStatusRequest($status);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Pet[]' === '\SplFileObject') {
@@ -704,7 +749,7 @@ public function findPetsByStatusWithHttpInfo($status)
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function findPetsByStatusAsync($status)
     {
@@ -724,15 +769,14 @@ function ($response) {
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function findPetsByStatusAsyncWithHttpInfo($status)
     {
         $returnType = '\OpenAPI\Client\Model\Pet[]';
         $request = $this->findPetsByStatusRequest($status);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -747,7 +791,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -756,9 +800,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -770,7 +814,7 @@ function ($exception) {
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function findPetsByStatusRequest($status)
     {
@@ -785,7 +829,7 @@ public function findPetsByStatusRequest($status)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -827,11 +871,11 @@ public function findPetsByStatusRequest($status)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -851,13 +895,11 @@ public function findPetsByStatusRequest($status)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -893,33 +935,31 @@ public function findPetsByTagsWithHttpInfo($tags)
         $request = $this->findPetsByTagsRequest($tags);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Pet[]' === '\SplFileObject') {
@@ -971,7 +1011,7 @@ public function findPetsByTagsWithHttpInfo($tags)
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function findPetsByTagsAsync($tags)
     {
@@ -991,15 +1031,14 @@ function ($response) {
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function findPetsByTagsAsyncWithHttpInfo($tags)
     {
         $returnType = '\OpenAPI\Client\Model\Pet[]';
         $request = $this->findPetsByTagsRequest($tags);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1014,7 +1053,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1023,9 +1062,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1037,7 +1076,7 @@ function ($exception) {
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function findPetsByTagsRequest($tags)
     {
@@ -1053,7 +1092,7 @@ public function findPetsByTagsRequest($tags)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -1095,11 +1134,11 @@ public function findPetsByTagsRequest($tags)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1119,13 +1158,11 @@ public function findPetsByTagsRequest($tags)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1161,33 +1198,31 @@ public function getPetByIdWithHttpInfo($pet_id)
         $request = $this->getPetByIdRequest($pet_id);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Pet' === '\SplFileObject') {
@@ -1239,7 +1274,7 @@ public function getPetByIdWithHttpInfo($pet_id)
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getPetByIdAsync($pet_id)
     {
@@ -1259,15 +1294,14 @@ function ($response) {
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getPetByIdAsyncWithHttpInfo($pet_id)
     {
         $returnType = '\OpenAPI\Client\Model\Pet';
         $request = $this->getPetByIdRequest($pet_id);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1282,7 +1316,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1291,9 +1325,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1305,7 +1339,7 @@ function ($exception) {
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function getPetByIdRequest($pet_id)
     {
@@ -1320,7 +1354,7 @@ public function getPetByIdRequest($pet_id)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1363,11 +1397,11 @@ public function getPetByIdRequest($pet_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1388,13 +1422,11 @@ public function getPetByIdRequest($pet_id)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1437,33 +1469,31 @@ public function updatePetWithHttpInfo($pet)
         $request = $this->updatePetRequest($pet);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -1485,7 +1515,7 @@ public function updatePetWithHttpInfo($pet)
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updatePetAsync($pet)
     {
@@ -1509,20 +1539,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updatePetAsyncWithHttpInfo($pet)
     {
         $returnType = '';
         $request = $this->updatePetRequest($pet);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1531,9 +1560,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1549,7 +1578,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Pet $pet Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function updatePetRequest($pet)
     {
@@ -1564,7 +1593,7 @@ public function updatePetRequest($pet)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1585,7 +1614,7 @@ public function updatePetRequest($pet)
         // for model (json/xml)
         if (isset($pet)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($pet));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($pet));
             } else {
                 $httpBody = $pet;
             }
@@ -1605,11 +1634,11 @@ public function updatePetRequest($pet)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1635,13 +1664,9 @@ public function updatePetRequest($pet)
         }
         $operationHost = $operationHosts[$this->hostIndex];
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PUT',
-            $operationHost . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PUT', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1680,33 +1705,31 @@ public function updatePetWithFormWithHttpInfo($pet_id, $name = null, $status = n
         $request = $this->updatePetWithFormRequest($pet_id, $name, $status);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -1726,7 +1749,7 @@ public function updatePetWithFormWithHttpInfo($pet_id, $name = null, $status = n
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updatePetWithFormAsync($pet_id, $name = null, $status = null)
     {
@@ -1748,20 +1771,19 @@ function ($response) {
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updatePetWithFormAsyncWithHttpInfo($pet_id, $name = null, $status = null)
     {
         $returnType = '';
         $request = $this->updatePetWithFormRequest($pet_id, $name, $status);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1770,9 +1792,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1786,7 +1808,7 @@ function ($exception) {
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function updatePetWithFormRequest($pet_id, $name = null, $status = null)
     {
@@ -1801,7 +1823,7 @@ public function updatePetWithFormRequest($pet_id, $name = null, $status = null)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1852,11 +1874,11 @@ public function updatePetWithFormRequest($pet_id, $name = null, $status = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1876,13 +1898,11 @@ public function updatePetWithFormRequest($pet_id, $name = null, $status = null)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1922,33 +1942,31 @@ public function uploadFileWithHttpInfo($pet_id, $additional_metadata = null, $fi
         $request = $this->uploadFileRequest($pet_id, $additional_metadata, $file);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\ApiResponse' === '\SplFileObject') {
@@ -2002,7 +2020,7 @@ public function uploadFileWithHttpInfo($pet_id, $additional_metadata = null, $fi
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function uploadFileAsync($pet_id, $additional_metadata = null, $file = null)
     {
@@ -2024,15 +2042,14 @@ function ($response) {
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function uploadFileAsyncWithHttpInfo($pet_id, $additional_metadata = null, $file = null)
     {
         $returnType = '\OpenAPI\Client\Model\ApiResponse';
         $request = $this->uploadFileRequest($pet_id, $additional_metadata, $file);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -2047,7 +2064,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -2056,9 +2073,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -2072,7 +2089,7 @@ function ($exception) {
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function uploadFileRequest($pet_id, $additional_metadata = null, $file = null)
     {
@@ -2087,7 +2104,7 @@ public function uploadFileRequest($pet_id, $additional_metadata = null, $file =
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -2146,11 +2163,11 @@ public function uploadFileRequest($pet_id, $additional_metadata = null, $file =
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2170,13 +2187,11 @@ public function uploadFileRequest($pet_id, $additional_metadata = null, $file =
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -2216,33 +2231,31 @@ public function uploadFileWithRequiredFileWithHttpInfo($pet_id, $required_file,
         $request = $this->uploadFileWithRequiredFileRequest($pet_id, $required_file, $additional_metadata);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\ApiResponse' === '\SplFileObject') {
@@ -2296,7 +2309,7 @@ public function uploadFileWithRequiredFileWithHttpInfo($pet_id, $required_file,
      * @param  string $additional_metadata Additional data to pass to server (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function uploadFileWithRequiredFileAsync($pet_id, $required_file, $additional_metadata = null)
     {
@@ -2318,15 +2331,14 @@ function ($response) {
      * @param  string $additional_metadata Additional data to pass to server (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function uploadFileWithRequiredFileAsyncWithHttpInfo($pet_id, $required_file, $additional_metadata = null)
     {
         $returnType = '\OpenAPI\Client\Model\ApiResponse';
         $request = $this->uploadFileWithRequiredFileRequest($pet_id, $required_file, $additional_metadata);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -2341,7 +2353,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -2350,9 +2362,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -2366,7 +2378,7 @@ function ($exception) {
      * @param  string $additional_metadata Additional data to pass to server (optional)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function uploadFileWithRequiredFileRequest($pet_id, $required_file, $additional_metadata = null)
     {
@@ -2387,7 +2399,7 @@ public function uploadFileWithRequiredFileRequest($pet_id, $required_file, $addi
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -2446,11 +2458,11 @@ public function uploadFileWithRequiredFileRequest($pet_id, $required_file, $addi
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -2470,31 +2482,76 @@ public function uploadFileWithRequiredFileRequest($pet_id, $required_file, $addi
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/StoreApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/StoreApi.php
index b69d2fcad456..b2a32ccc8123 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/StoreApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/StoreApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * StoreApi Class Doc Comment
@@ -49,9 +65,19 @@
 class StoreApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class StoreApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
      */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
+     */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -146,33 +205,31 @@ public function deleteOrderWithHttpInfo($order_id)
         $request = $this->deleteOrderRequest($order_id);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -190,7 +247,7 @@ public function deleteOrderWithHttpInfo($order_id)
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deleteOrderAsync($order_id)
     {
@@ -210,20 +267,19 @@ function ($response) {
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deleteOrderAsyncWithHttpInfo($order_id)
     {
         $returnType = '';
         $request = $this->deleteOrderRequest($order_id);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -232,9 +288,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -246,7 +302,7 @@ function ($exception) {
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function deleteOrderRequest($order_id)
     {
@@ -261,7 +317,7 @@ public function deleteOrderRequest($order_id)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -304,11 +360,11 @@ public function deleteOrderRequest($order_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -324,13 +380,11 @@ public function deleteOrderRequest($order_id)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'DELETE',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('DELETE', $uri, $headers, $httpBody);
     }
 
     /**
@@ -364,33 +418,31 @@ public function getInventoryWithHttpInfo()
         $request = $this->getInventoryRequest();
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('array<string,int>' === '\SplFileObject') {
@@ -441,7 +493,7 @@ public function getInventoryWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getInventoryAsync()
     {
@@ -460,15 +512,14 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getInventoryAsyncWithHttpInfo()
     {
         $returnType = 'array<string,int>';
         $request = $this->getInventoryRequest();
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -483,7 +534,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -492,9 +543,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -505,7 +556,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function getInventoryRequest()
     {
@@ -514,7 +565,7 @@ public function getInventoryRequest()
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -549,11 +600,11 @@ public function getInventoryRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -574,13 +625,11 @@ public function getInventoryRequest()
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -616,33 +665,31 @@ public function getOrderByIdWithHttpInfo($order_id)
         $request = $this->getOrderByIdRequest($order_id);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Order' === '\SplFileObject') {
@@ -694,7 +741,7 @@ public function getOrderByIdWithHttpInfo($order_id)
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getOrderByIdAsync($order_id)
     {
@@ -714,15 +761,14 @@ function ($response) {
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getOrderByIdAsyncWithHttpInfo($order_id)
     {
         $returnType = '\OpenAPI\Client\Model\Order';
         $request = $this->getOrderByIdRequest($order_id);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -737,7 +783,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -746,9 +792,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -760,7 +806,7 @@ function ($exception) {
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function getOrderByIdRequest($order_id)
     {
@@ -782,7 +828,7 @@ public function getOrderByIdRequest($order_id)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -825,11 +871,11 @@ public function getOrderByIdRequest($order_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -845,13 +891,11 @@ public function getOrderByIdRequest($order_id)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -887,33 +931,31 @@ public function placeOrderWithHttpInfo($order)
         $request = $this->placeOrderRequest($order);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\Order' === '\SplFileObject') {
@@ -965,7 +1007,7 @@ public function placeOrderWithHttpInfo($order)
      * @param  \OpenAPI\Client\Model\Order $order order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function placeOrderAsync($order)
     {
@@ -985,15 +1027,14 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\Order $order order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function placeOrderAsyncWithHttpInfo($order)
     {
         $returnType = '\OpenAPI\Client\Model\Order';
         $request = $this->placeOrderRequest($order);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1008,7 +1049,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1017,9 +1058,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1031,7 +1072,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\Order $order order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function placeOrderRequest($order)
     {
@@ -1046,7 +1087,7 @@ public function placeOrderRequest($order)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1067,7 +1108,7 @@ public function placeOrderRequest($order)
         // for model (json/xml)
         if (isset($order)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($order));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($order));
             } else {
                 $httpBody = $order;
             }
@@ -1087,11 +1128,11 @@ public function placeOrderRequest($order)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1107,31 +1148,76 @@ public function placeOrderRequest($order)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/UserApi.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/UserApi.php
index 621d0ae7e48a..fbf3f05d9a41 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Api/UserApi.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Api/UserApi.php
@@ -27,16 +27,32 @@
 
 namespace OpenAPI\Client\Api;
 
-use GuzzleHttp\Client;
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\MultipartStream;
-use GuzzleHttp\Psr7\Request;
-use GuzzleHttp\RequestOptions;
+use GuzzleHttp\Psr7\Query;
+use Http\Client\Common\Plugin\ErrorPlugin;
+use Http\Client\Common\Plugin\RedirectPlugin;
+use Http\Client\Common\PluginClient;
+use Http\Client\Common\PluginClientFactory;
+use Http\Client\Exception\HttpException;
+use Http\Client\HttpAsyncClient;
+use Http\Discovery\HttpAsyncClientDiscovery;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use Http\Message\RequestFactory;
+use Http\Promise\Promise;
 use OpenAPI\Client\ApiException;
 use OpenAPI\Client\Configuration;
+use OpenAPI\Client\DebugPlugin;
 use OpenAPI\Client\HeaderSelector;
 use OpenAPI\Client\ObjectSerializer;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+use Psr\Http\Message\UriInterface;
+use function sprintf;
 
 /**
  * UserApi Class Doc Comment
@@ -49,9 +65,19 @@
 class UserApi
 {
     /**
-     * @var ClientInterface
+     * @var PluginClient
      */
-    protected $client;
+    protected $httpClient;
+
+    /**
+     * @var PluginClient
+     */
+    protected $httpAsyncClient;
+
+    /**
+     * @var UriFactoryInterface
+     */
+    protected $uriFactory;
 
     /**
      * @var Configuration
@@ -69,20 +95,53 @@ class UserApi
     protected $hostIndex;
 
     /**
-     * @param ClientInterface $client
-     * @param Configuration   $config
-     * @param HeaderSelector  $selector
-     * @param int             $hostIndex (Optional) host index to select the list of hosts if defined in the OpenAPI spec
+     * @var RequestFactoryInterface
      */
+    protected $requestFactory;
+
+    /**
+     * @var StreamFactoryInterface
+     */
+    protected $streamFactory;
+
     public function __construct(
-        ClientInterface $client = null,
+        ClientInterface $httpClient = null,
         Configuration $config = null,
+        HttpAsyncClient $httpAsyncClient = null,
+        UriFactoryInterface $uriFactory = null,
+        RequestFactoryInterface $requestFactory = null,
+        StreamFactoryInterface $streamFactory = null,
         HeaderSelector $selector = null,
+        ?array $plugins = null,
         $hostIndex = 0
     ) {
-        $this->client = $client ?: new Client();
-        $this->config = $config ?: new Configuration();
-        $this->headerSelector = $selector ?: new HeaderSelector();
+        $this->config = $config ?? (new Configuration())->setHost('http://petstore.swagger.io:80/v2');
+        $this->requestFactory = $requestFactory ?? Psr17FactoryDiscovery::findRequestFactory();
+        $this->streamFactory = $streamFactory ?? Psr17FactoryDiscovery::findStreamFactory();
+
+        $plugins = $plugins ?? [
+            new RedirectPlugin(['strict' => true]),
+            new ErrorPlugin(),
+        ];
+
+        if ($this->config->getDebug()) {
+            $plugins[] = new DebugPlugin(fopen($this->config->getDebugFile(), 'ab'));
+        }
+
+        $this->httpClient = (new PluginClientFactory())->createClient(
+            $httpClient ?? Psr18ClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->httpAsyncClient = (new PluginClientFactory())->createClient(
+            $httpAsyncClient ?? HttpAsyncClientDiscovery::find(),
+            $plugins
+        );
+
+        $this->uriFactory = $uriFactory ?? Psr17FactoryDiscovery::findUriFactory();
+
+        $this->headerSelector = $selector ?? new HeaderSelector();
+
         $this->hostIndex = $hostIndex;
     }
 
@@ -146,33 +205,31 @@ public function createUserWithHttpInfo($user)
         $request = $this->createUserRequest($user);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -190,7 +247,7 @@ public function createUserWithHttpInfo($user)
      * @param  \OpenAPI\Client\Model\User $user Created user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUserAsync($user)
     {
@@ -210,20 +267,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\User $user Created user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUserAsyncWithHttpInfo($user)
     {
         $returnType = '';
         $request = $this->createUserRequest($user);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -232,9 +288,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -246,7 +302,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\User $user Created user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function createUserRequest($user)
     {
@@ -261,7 +317,7 @@ public function createUserRequest($user)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -282,7 +338,7 @@ public function createUserRequest($user)
         // for model (json/xml)
         if (isset($user)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($user));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($user));
             } else {
                 $httpBody = $user;
             }
@@ -302,11 +358,11 @@ public function createUserRequest($user)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -322,13 +378,11 @@ public function createUserRequest($user)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -363,33 +417,31 @@ public function createUsersWithArrayInputWithHttpInfo($user)
         $request = $this->createUsersWithArrayInputRequest($user);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -407,7 +459,7 @@ public function createUsersWithArrayInputWithHttpInfo($user)
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUsersWithArrayInputAsync($user)
     {
@@ -427,20 +479,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUsersWithArrayInputAsyncWithHttpInfo($user)
     {
         $returnType = '';
         $request = $this->createUsersWithArrayInputRequest($user);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -449,9 +500,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -463,7 +514,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function createUsersWithArrayInputRequest($user)
     {
@@ -478,7 +529,7 @@ public function createUsersWithArrayInputRequest($user)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -499,7 +550,7 @@ public function createUsersWithArrayInputRequest($user)
         // for model (json/xml)
         if (isset($user)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($user));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($user));
             } else {
                 $httpBody = $user;
             }
@@ -519,11 +570,11 @@ public function createUsersWithArrayInputRequest($user)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -539,13 +590,11 @@ public function createUsersWithArrayInputRequest($user)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -580,33 +629,31 @@ public function createUsersWithListInputWithHttpInfo($user)
         $request = $this->createUsersWithListInputRequest($user);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -624,7 +671,7 @@ public function createUsersWithListInputWithHttpInfo($user)
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUsersWithListInputAsync($user)
     {
@@ -644,20 +691,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function createUsersWithListInputAsyncWithHttpInfo($user)
     {
         $returnType = '';
         $request = $this->createUsersWithListInputRequest($user);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -666,9 +712,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -680,7 +726,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\User[] $user List of user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function createUsersWithListInputRequest($user)
     {
@@ -695,7 +741,7 @@ public function createUsersWithListInputRequest($user)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -716,7 +762,7 @@ public function createUsersWithListInputRequest($user)
         // for model (json/xml)
         if (isset($user)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($user));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($user));
             } else {
                 $httpBody = $user;
             }
@@ -736,11 +782,11 @@ public function createUsersWithListInputRequest($user)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -756,13 +802,11 @@ public function createUsersWithListInputRequest($user)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'POST',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('POST', $uri, $headers, $httpBody);
     }
 
     /**
@@ -797,33 +841,31 @@ public function deleteUserWithHttpInfo($username)
         $request = $this->deleteUserRequest($username);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -841,7 +883,7 @@ public function deleteUserWithHttpInfo($username)
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deleteUserAsync($username)
     {
@@ -861,20 +903,19 @@ function ($response) {
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function deleteUserAsyncWithHttpInfo($username)
     {
         $returnType = '';
         $request = $this->deleteUserRequest($username);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -883,9 +924,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -897,7 +938,7 @@ function ($exception) {
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function deleteUserRequest($username)
     {
@@ -912,7 +953,7 @@ public function deleteUserRequest($username)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -955,11 +996,11 @@ public function deleteUserRequest($username)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -975,13 +1016,11 @@ public function deleteUserRequest($username)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'DELETE',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('DELETE', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1017,33 +1056,31 @@ public function getUserByNameWithHttpInfo($username)
         $request = $this->getUserByNameRequest($username);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('\OpenAPI\Client\Model\User' === '\SplFileObject') {
@@ -1095,7 +1132,7 @@ public function getUserByNameWithHttpInfo($username)
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getUserByNameAsync($username)
     {
@@ -1115,15 +1152,14 @@ function ($response) {
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function getUserByNameAsyncWithHttpInfo($username)
     {
         $returnType = '\OpenAPI\Client\Model\User';
         $request = $this->getUserByNameRequest($username);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1138,7 +1174,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1147,9 +1183,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1161,7 +1197,7 @@ function ($exception) {
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function getUserByNameRequest($username)
     {
@@ -1176,7 +1212,7 @@ public function getUserByNameRequest($username)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1219,11 +1255,11 @@ public function getUserByNameRequest($username)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1239,13 +1275,11 @@ public function getUserByNameRequest($username)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1283,33 +1317,31 @@ public function loginUserWithHttpInfo($username, $password)
         $request = $this->loginUserRequest($username, $password);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             switch($statusCode) {
                 case 200:
                     if ('string' === '\SplFileObject') {
@@ -1362,7 +1394,7 @@ public function loginUserWithHttpInfo($username, $password)
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function loginUserAsync($username, $password)
     {
@@ -1383,15 +1415,14 @@ function ($response) {
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function loginUserAsyncWithHttpInfo($username, $password)
     {
         $returnType = 'string';
         $request = $this->loginUserRequest($username, $password);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     if ($returnType === '\SplFileObject') {
@@ -1406,7 +1437,7 @@ function ($response) use ($returnType) {
                         $response->getHeaders()
                     ];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1415,9 +1446,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1430,7 +1461,7 @@ function ($exception) {
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function loginUserRequest($username, $password)
     {
@@ -1451,7 +1482,7 @@ public function loginUserRequest($username, $password)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
         // query params
@@ -1508,11 +1539,11 @@ public function loginUserRequest($username, $password)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1528,13 +1559,11 @@ public function loginUserRequest($username, $password)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1567,33 +1596,31 @@ public function logoutUserWithHttpInfo()
         $request = $this->logoutUserRequest();
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -1610,7 +1637,7 @@ public function logoutUserWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function logoutUserAsync()
     {
@@ -1629,20 +1656,19 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function logoutUserAsyncWithHttpInfo()
     {
         $returnType = '';
         $request = $this->logoutUserRequest();
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1651,9 +1677,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1664,7 +1690,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function logoutUserRequest()
     {
@@ -1673,7 +1699,7 @@ public function logoutUserRequest()
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1708,11 +1734,11 @@ public function logoutUserRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1728,13 +1754,11 @@ public function logoutUserRequest()
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'GET',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('GET', $uri, $headers, $httpBody);
     }
 
     /**
@@ -1771,33 +1795,31 @@ public function updateUserWithHttpInfo($username, $user)
         $request = $this->updateUserRequest($username, $user);
 
         try {
-            $options = $this->createHttpClientOption();
             try {
-                $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
-                throw new ApiException(
-                    "[{$e->getCode()}] {$e->getMessage()}",
-                    (int) $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? (string) $e->getResponse()->getBody() : null
-                );
-            }
-
-            $statusCode = $response->getStatusCode();
-
-            if ($statusCode < 200 || $statusCode > 299) {
+                $response = $this->httpClient->sendRequest($request);
+            } catch (HttpException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     sprintf(
                         '[%d] Error connecting to the API (%s)',
-                        $statusCode,
+                        $response->getStatusCode(),
                         (string) $request->getUri()
                     ),
-                    $statusCode,
-                    $response->getHeaders(),
-                    (string) $response->getBody()
+                    $request,
+                    $response,
+                    $e
+                );
+            } catch (ClientExceptionInterface $e) {
+                throw new ApiException(
+                    "[{$e->getCode()}] {$e->getMessage()}",
+                    $request,
+                    null,
+                    $e
                 );
             }
 
+            $statusCode = $response->getStatusCode();
+
             return [null, $statusCode, $response->getHeaders()];
 
         } catch (ApiException $e) {
@@ -1816,7 +1838,7 @@ public function updateUserWithHttpInfo($username, $user)
      * @param  \OpenAPI\Client\Model\User $user Updated user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updateUserAsync($username, $user)
     {
@@ -1837,20 +1859,19 @@ function ($response) {
      * @param  \OpenAPI\Client\Model\User $user Updated user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Promise\PromiseInterface
+     * @return Promise
      */
     public function updateUserAsyncWithHttpInfo($username, $user)
     {
         $returnType = '';
         $request = $this->updateUserRequest($username, $user);
 
-        return $this->client
-            ->sendAsync($request, $this->createHttpClientOption())
+        return $this->httpAsyncClient->sendAsyncRequest($request)
             ->then(
                 function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
-                function ($exception) {
+                function (HttpException $exception) {
                     $response = $exception->getResponse();
                     $statusCode = $response->getStatusCode();
                     throw new ApiException(
@@ -1859,9 +1880,9 @@ function ($exception) {
                             $statusCode,
                             $exception->getRequest()->getUri()
                         ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        (string) $response->getBody()
+                        $exception->getRequest(),
+                        $exception->getResponse(),
+                        $exception
                     );
                 }
             );
@@ -1874,7 +1895,7 @@ function ($exception) {
      * @param  \OpenAPI\Client\Model\User $user Updated user object (required)
      *
      * @throws \InvalidArgumentException
-     * @return \GuzzleHttp\Psr7\Request
+     * @return RequestInterface
      */
     public function updateUserRequest($username, $user)
     {
@@ -1895,7 +1916,7 @@ public function updateUserRequest($username, $user)
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
-        $httpBody = '';
+        $httpBody = null;
         $multipart = false;
 
 
@@ -1924,7 +1945,7 @@ public function updateUserRequest($username, $user)
         // for model (json/xml)
         if (isset($user)) {
             if ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($user));
+                $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($user));
             } else {
                 $httpBody = $user;
             }
@@ -1944,11 +1965,11 @@ public function updateUserRequest($username, $user)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams);
 
             } else {
                 // for HTTP post (form)
-                $httpBody = \GuzzleHttp\Psr7\build_query($formParams);
+                $httpBody = Query::build($formParams);
             }
         }
 
@@ -1964,31 +1985,76 @@ public function updateUserRequest($username, $user)
             $headers
         );
 
-        $query = \GuzzleHttp\Psr7\build_query($queryParams);
-        return new Request(
-            'PUT',
-            $this->config->getHost() . $resourcePath . ($query ? "?{$query}" : ''),
-            $headers,
-            $httpBody
-        );
+        $operationHost = $this->config->getHost();
+
+        $uri = $this->createUri($operationHost, $resourcePath, $queryParams);
+
+        return $this->createRequest('PUT', $uri, $headers, $httpBody);
     }
 
+
     /**
-     * Create http client option
+     * @param string $method
+     * @param string|UriInterface $uri
+     * @param array $headers
+     * @param string|StreamInterface|null $body
      *
-     * @throws \RuntimeException on file opening failure
-     * @return array of http client options
+     * @return RequestInterface
      */
-    protected function createHttpClientOption()
+    protected function createRequest(string $method, $uri, array $headers = [], $body = null): RequestInterface
     {
-        $options = [];
-        if ($this->config->getDebug()) {
-            $options[RequestOptions::DEBUG] = fopen($this->config->getDebugFile(), 'a');
-            if (!$options[RequestOptions::DEBUG]) {
-                throw new \RuntimeException('Failed to open the debug file: ' . $this->config->getDebugFile());
-            }
+        if ($this->requestFactory instanceof RequestFactory) {
+            return $this->requestFactory->createRequest(
+                $method,
+                $uri,
+                $headers,
+                $body
+            );
+        }
+
+        if (is_string($body) && '' !== $body && null === $this->streamFactory) {
+            throw new \RuntimeException('Cannot create request: A stream factory is required to create a request with a non-empty string body.');
+        }
+
+        $request = $this->requestFactory->createRequest($method, $uri);
+
+        foreach ($headers as $key => $value) {
+            $request = $request->withHeader($key, $value);
+        }
+
+        if (null !== $body && '' !== $body) {
+            $request = $request->withBody(
+                is_string($body) ? $this->streamFactory->createStream($body) : $body
+            );
+        }
+
+        return $request;
+    }
+
+    private function createUri(
+        string $operationHost,
+        string $resourcePath,
+        array $queryParams
+    ): UriInterface {
+        $parsedUrl = parse_url($operationHost);
+
+        $host = $parsedUrl['host'] ?? null;
+        $scheme = $parsedUrl['scheme'] ?? null;
+        $basePath = $parsedUrl['path'] ?? null;
+        $port = $parsedUrl['port'] ?? null;
+        $user = $parsedUrl['user'] ?? null;
+        $password = $parsedUrl['pass'] ?? null;
+
+        $uri = $this->uriFactory->createUri($basePath . $resourcePath)
+            ->withHost($host)
+            ->withScheme($scheme)
+            ->withPort($port)
+            ->withQuery(Query::build($queryParams));
+
+        if ($user) {
+            $uri = $uri->withUserInfo($user, $password);
         }
 
-        return $options;
+        return $uri;
     }
 }
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php b/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
index dbf0b74a5de2..3569234d05fb 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
@@ -27,7 +27,10 @@
 
 namespace OpenAPI\Client;
 
-use \Exception;
+use Exception;
+use Http\Client\Exception\RequestException;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * ApiException Class Doc Comment
@@ -37,13 +40,13 @@
  * @author   OpenAPI Generator team
  * @link     https://openapi-generator.tech
  */
-class ApiException extends Exception
+class ApiException extends RequestException
 {
 
     /**
      * The HTTP body of the server response either as Json or string.
      *
-     * @var \stdClass|string|null
+     * @var string|null
      */
     protected $responseBody;
 
@@ -61,19 +64,18 @@ class ApiException extends Exception
      */
     protected $responseObject;
 
-    /**
-     * Constructor
-     *
-     * @param string                $message         Error message
-     * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
-     * @param \stdClass|string|null $responseBody    HTTP decoded body of the server response either as \stdClass or string
-     */
-    public function __construct($message = "", $code = 0, $responseHeaders = [], $responseBody = null)
-    {
-        parent::__construct($message, $code);
-        $this->responseHeaders = $responseHeaders;
-        $this->responseBody = $responseBody;
+    public function __construct(
+        $message,
+        RequestInterface $request,
+        ResponseInterface $response = null,
+        Exception $previous = null
+    ) {
+        parent::__construct($message, $request, $previous);
+        if ($response) {
+            $this->responseHeaders = $response->getHeaders();
+            $this->responseBody = (string) $response->getBody();
+            $this->code = $response->getStatusCode();
+        }
     }
 
     /**
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/DebugPlugin.php b/samples/client/petstore/php/OpenAPIClient-php/lib/DebugPlugin.php
new file mode 100644
index 000000000000..b0d3a3b40beb
--- /dev/null
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/DebugPlugin.php
@@ -0,0 +1,101 @@
+<?php
+/**
+ * Configuration
+ * PHP version 7.2
+ *
+ * @category Class
+ * @package  OpenAPI\Client
+ * @author   OpenAPI Generator team
+ * @link     https://openapi-generator.tech
+ */
+
+/**
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://openapi-generator.tech
+ * OpenAPI Generator version: 6.0.0-SNAPSHOT
+ */
+
+/**
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+namespace OpenAPI\Client;
+
+use Http\Client\Common\Plugin;
+use Http\Promise\Promise;
+use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use function is_resource;
+
+/**
+ * Configuration Class Doc Comment
+ * PHP version 7.2
+ *
+ * @category Class
+ * @package  OpenAPI\Client
+ * @author   OpenAPI Generator team
+ * @link     https://openapi-generator.tech
+ */
+class DebugPlugin implements Plugin
+{
+
+    /**
+     * @var resource
+     */
+    private $output;
+
+    /**
+     * DebuggingPlugin constructor.
+     *
+     * @param resource $output
+     */
+    public function __construct($output)
+    {
+        if (!is_resource($output)) {
+            throw new \InvalidArgumentException('debugging resource is not valid');
+        }
+        $this->output = $output;
+    }
+
+    public function handleRequest(RequestInterface $request, callable $next, callable $first): Promise
+    {
+        return $next($request)->then(
+            function (ResponseInterface $response) use ($request) {
+                $this->logSuccess($request, $response);
+
+                return $response;
+            },
+            function (ClientExceptionInterface $exception) use ($request) {
+                $this->logError($request, $exception);
+
+                throw $exception;
+            }
+        );
+    }
+
+    private function logSuccess(RequestInterface $request, ResponseInterface $response): void
+    {
+        $methodAndPath = $request->getMethod() . ' ' . $request->getUri()->getPath();
+        $protocol = $response->getProtocolVersion();
+        $responseCode = $response->getStatusCode();
+        \fprintf($this->output, '<%s HTTP/%s> %s', $methodAndPath, $protocol, $responseCode);
+        \fwrite($this->output, "\n");
+    }
+
+    private function logError(RequestInterface $request, ClientExceptionInterface $exception): void
+    {
+        $methodAndPath = $request->getMethod() . ' ' . $request->getUri()->getPath();
+        $protocol = $request->getProtocolVersion();
+        $error = $exception->getMessage();
+        $responseCode = $exception->getCode();
+        \fprintf($this->output, '<%s HTTP/%s> %s %s', $methodAndPath, $responseCode, $error, $protocol);
+        \fwrite($this->output, "\n");
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/php/OpenAPIClient-php/tests/FakeHttpClient.php b/samples/client/petstore/php/OpenAPIClient-php/tests/FakeHttpClient.php
index d93b8f8b0b36..7fbb64005a12 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/tests/FakeHttpClient.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/tests/FakeHttpClient.php
@@ -2,9 +2,7 @@
 
 namespace OpenAPI\Client;
 
-use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\GuzzleException;
-use GuzzleHttp\Psr7\Response;
+use Psr\Http\Client\ClientInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
 
@@ -31,39 +29,9 @@ public function setResponse(ResponseInterface $response = null)
         $this->response = $response;
     }
 
-    /**
-     * Send an HTTP request.
-     *
-     * @param RequestInterface $request Request to send
-     * @param array $options Request options to apply to the given
-     *                                  request and to the transfer.
-     *
-     * @return ResponseInterface
-     * @throws GuzzleException
-     */
-    public function send(RequestInterface $request, array $options = [])
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         $this->request = $request;
-        return $this->response ?: new Response(200);
-    }
-
-    public function sendAsync(RequestInterface $request, array $options = [])
-    {
-        throw new \RuntimeException('not implemented');
-    }
-
-    public function request($method, $uri, array $options = [])
-    {
-        throw new \RuntimeException('not implemented');
-    }
-
-    public function requestAsync($method, $uri, array $options = [])
-    {
-        throw new \RuntimeException('not implemented');
-    }
-
-    public function getConfig($option = null)
-    {
-        throw new \RuntimeException('not implemented');
+        return $this->response ?: new \GuzzleHttp\Psr7\Response(200);
     }
 }