[java][resttemplate] Fix model combining properties and additional pr…

…operties

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java

@@ -583,6 +583,14 @@ public void processOpts() {
         } else if (RESTTEMPLATE.equals(getLibrary())) {
             forceSerializationLibrary(SERIALIZATION_LIBRARY_JACKSON);
             supportingFiles.add(new SupportingFile("auth/Authentication.mustache", authFolder, "Authentication.java"));
+
+            // Composed schemas can have the 'additionalProperties' keyword, as specified in JSON schema.
+            // In principle, this should be enabled by default for all code generators. However due to limitations
+            // in other code generators, support needs to be enabled on a case-by-case basis.
+            // The flag below should be set for all Java libraries, but the templates need to be ported
+            // one by one for each library.
+            supportsAdditionalPropertiesWithComposedSchema = true;
+
         } else if (WEBCLIENT.equals(getLibrary())) {
             forceSerializationLibrary(SERIALIZATION_LIBRARY_JACKSON);
         } else if (RESTCLIENT.equals(getLibrary())) {

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/additional_properties.mustache

@@ -0,0 +1,45 @@
+{{#additionalPropertiesType}}
+  /**
+   * A container for additional, undeclared properties.
+   * This is a holder for any undeclared properties as specified with
+   * the 'additionalProperties' keyword in the OAS document.
+   */
+  private Map<String, {{{.}}}> additionalProperties;
+
+  /**
+   * Set the additional (undeclared) property with the specified name and value.
+   * If the property does not already exist, create it otherwise replace it.
+   * @param key the name of the property
+   * @param value the value of the property
+   * @return self reference
+   */
+  @JsonAnySetter
+  public {{classname}} putAdditionalProperty(String key, {{{.}}} value) {
+    if (this.additionalProperties == null) {
+        this.additionalProperties = new HashMap<String, {{{.}}}>();
+    }
+    this.additionalProperties.put(key, value);
+    return this;
+  }
+
+  /**
+   * Return the additional (undeclared) properties.
+   * @return the additional (undeclared) properties
+   */
+  @JsonAnyGetter
+  public Map<String, {{{.}}}> getAdditionalProperties() {
+    return additionalProperties;
+  }
+
+  /**
+   * Return the additional (undeclared) property with the specified name.
+   * @param key the name of the property
+   * @return the additional (undeclared) property with the specified name
+   */
+  public {{{.}}} getAdditionalProperty(String key) {
+    if (this.additionalProperties == null) {
+        return null;
+    }
+    return this.additionalProperties.get(key);
+  }
+{{/additionalPropertiesType}}

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/model.mustache

@@ -0,0 +1,78 @@
+{{>licenseInfo}}
+
+package {{package}};
+
+{{#useReflectionEqualsHashCode}}
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.apache.commons.lang3.builder.HashCodeBuilder;
+{{/useReflectionEqualsHashCode}}
+{{#models}}
+{{#model}}
+{{#additionalPropertiesType}}
+import java.util.Map;
+import java.util.HashMap;
+import com.fasterxml.jackson.annotation.JsonAnyGetter;
+import com.fasterxml.jackson.annotation.JsonAnySetter;
+{{/additionalPropertiesType}}
+{{/model}}
+{{/models}}
+import java.util.Objects;
+import java.util.Arrays;
+{{#imports}}
+import {{import}};
+{{/imports}}
+{{#serializableModel}}
+import java.io.Serializable;
+{{/serializableModel}}
+{{#jackson}}
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+{{#withXml}}
+import com.fasterxml.jackson.dataformat.xml.annotation.*;
+{{/withXml}}
+{{#vendorExtensions.x-has-readonly-properties}}
+import com.fasterxml.jackson.annotation.JsonCreator;
+{{/vendorExtensions.x-has-readonly-properties}}
+{{/jackson}}
+{{#withXml}}
+import {{javaxPackage}}.xml.bind.annotation.*;
+import {{javaxPackage}}.xml.bind.annotation.adapters.*;
+import io.github.threetenjaxb.core.*;
+{{/withXml}}
+{{#jsonb}}
+import java.lang.reflect.Type;
+import {{javaxPackage}}.json.bind.annotation.JsonbTypeDeserializer;
+import {{javaxPackage}}.json.bind.annotation.JsonbTypeSerializer;
+import {{javaxPackage}}.json.bind.serializer.DeserializationContext;
+import {{javaxPackage}}.json.bind.serializer.JsonbDeserializer;
+import {{javaxPackage}}.json.bind.serializer.JsonbSerializer;
+import {{javaxPackage}}.json.bind.serializer.SerializationContext;
+import {{javaxPackage}}.json.stream.JsonGenerator;
+import {{javaxPackage}}.json.stream.JsonParser;
+import {{javaxPackage}}.json.bind.annotation.JsonbProperty;
+{{#vendorExtensions.x-has-readonly-properties}}
+import {{javaxPackage}}.json.bind.annotation.JsonbCreator;
+{{/vendorExtensions.x-has-readonly-properties}}
+{{/jsonb}}
+{{#parcelableModel}}
+import android.os.Parcelable;
+import android.os.Parcel;
+{{/parcelableModel}}
+{{#useBeanValidation}}
+import {{javaxPackage}}.validation.constraints.*;
+import {{javaxPackage}}.validation.Valid;
+{{/useBeanValidation}}
+{{#performBeanValidation}}
+import org.hibernate.validator.constraints.*;
+{{/performBeanValidation}}
+{{#supportUrlQuery}}
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.StringJoiner;
+{{/supportUrlQuery}}
+
+{{#models}}
+{{#model}}
+{{#isEnum}}{{>modelEnum}}{{/isEnum}}{{^isEnum}}{{#vendorExtensions.x-is-one-of-interface}}{{>oneof_interface}}{{/vendorExtensions.x-is-one-of-interface}}{{^vendorExtensions.x-is-one-of-interface}}{{>pojo}}{{/vendorExtensions.x-is-one-of-interface}}{{/isEnum}}
+{{/model}}
+{{/models}}