Opinionated code cleanup: use Objects#nonNull (#116)

* Change code using "!= null" to use Objects#nonNull instead
* In BasicAuthenticationInterceptor, add static import for
Collections#singletonList

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/BasicAuthenticationInterceptor.java

@@ -1,5 +1,8 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
+import static java.util.Collections.singletonList;
+import static java.util.Objects.nonNull;
+
 import io.dropwizard.auth.AuthenticationException;
 import io.dropwizard.auth.basic.BasicCredentials;
 import org.apache.cxf.common.security.SecurityToken;
@@ -18,7 +21,6 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.net.HttpURLConnection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -57,12 +59,12 @@ public void handleMessage(final Message message) throws Fault {
 
         try {
             var policy = message.get(AuthorizationPolicy.class);
-            if (policy != null && policy.getUserName() != null && policy.getPassword() != null) {
+            if (nonNull(policy) && nonNull(policy.getUserName()) && nonNull(policy.getPassword())) {
                 credentials = new BasicCredentials(policy.getUserName(), policy.getPassword());
             } else {
                 // try the WS-Security UsernameToken
                 var token = message.get(SecurityToken.class);
-                if (token != null && token.getTokenType() == TokenType.UsernameToken) {
+                if (nonNull(token) && token.getTokenType() == TokenType.UsernameToken) {
                     var usernameToken = (UsernameToken) token;
                     credentials = new BasicCredentials(usernameToken.getName(), usernameToken.getPassword());
                 }
@@ -94,9 +96,9 @@ private void sendErrorResponse(Message message, int responseCode) {
         // Set the response headers
         @SuppressWarnings("unchecked")
         var responseHeaders = (Map<String, List<String>>) message.get(Message.PROTOCOL_HEADERS);
-        if (responseHeaders != null) {
-            responseHeaders.put("WWW-Authenticate", Collections.singletonList("Basic realm=" + authentication.getRealm()));
-            responseHeaders.put("Content-length", Collections.singletonList("0"));
+        if (nonNull(responseHeaders)) {
+            responseHeaders.put("WWW-Authenticate", singletonList("Basic realm=" + authentication.getRealm()));
+            responseHeaders.put("Content-length", singletonList("0"));
         }
         message.getInterceptorChain().abort();
         try {

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/ClientBuilder.java

@@ -1,6 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.nonNull;
 
 import com.google.common.collect.ImmutableList;
 import jakarta.xml.ws.handler.Handler;
@@ -50,8 +51,8 @@ public String getBindingId() {
      * @param address      Endpoint URL address..
      */
     public ClientBuilder(Class<T> serviceClass, String address) {
-        checkArgument(serviceClass != null, "ServiceClass is null");
-        checkArgument(address != null, "Address is null");
+        checkArgument(nonNull(serviceClass), "ServiceClass is null");
+        checkArgument(nonNull(address), "Address is null");
         checkArgument(!address.isBlank(), "Address is empty");
         this.serviceClass = serviceClass;
         this.address = address;

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/EndpointBuilder.java

@@ -1,6 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.nonNull;
 
 import org.apache.cxf.interceptor.Interceptor;
 import org.apache.cxf.message.Message;
@@ -51,8 +52,8 @@ public Map<String, Object> getProperties() {
      * @param service Service implementation.
      */
     public EndpointBuilder(String path, Object service) {
-        checkArgument(service != null, "Service is null");
-        checkArgument(path != null, "Path is null");
+        checkArgument(nonNull(service), "Service is null");
+        checkArgument(nonNull(path), "Path is null");
         checkArgument(!path.isBlank(), "Path is empty");
         if (!path.startsWith("local:")) { // local transport is used in tests
             path = (path.startsWith("/")) ? path : "/" + path;

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/InstrumentedInvokerFactory.java

@@ -1,5 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
+import static java.util.Objects.nonNull;
+
 import com.codahale.metrics.Meter;
 import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.Timer;
@@ -87,7 +89,7 @@ private Invoker exceptionMetered(Invoker invoker, List<Method> meteredMethods) {
      * @see com.codahale.metrics.jersey3.InstrumentedResourceMethodApplicationListener
      */
     private String chooseName(String explicitName, boolean absolute, Method method, String... suffixes) {
-        if (explicitName != null && !explicitName.isEmpty()) {
+        if (nonNull(explicitName) && !explicitName.isEmpty()) {
             if (absolute) {
                 return explicitName;
             }

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/InstrumentedInvokers.java

@@ -1,5 +1,6 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
+import static java.util.Objects.nonNull;
 import static java.util.Objects.requireNonNull;
 
 import com.codahale.metrics.Meter;
@@ -123,7 +124,7 @@ public Object invoke(Exchange exchange, Object o) {
                     var exceptionMeter = requireNonNull(meters.get(methodName));
                     var exceptionClass = exceptionMeter.getExceptionClass();
                     if (exceptionClass.isAssignableFrom(e.getClass()) ||
-                            (e.getCause() != null &&
+                            (nonNull(e.getCause()) &&
                                     exceptionClass.isAssignableFrom(e.getCause().getClass()))) {
                         exceptionMeter.getMeter().mark();
                     }

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/JakartaXmlWsBundle.java

@@ -1,6 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.nonNull;
 
 import io.dropwizard.core.ConfiguredBundle;
 import io.dropwizard.core.setup.Bootstrap;
@@ -42,9 +43,9 @@ public JakartaXmlWsBundle(String servletPath) {
      * @param jwsEnvironment Valid JakartaXmlWsEnvironment.
      */
     public JakartaXmlWsBundle(String servletPath, JakartaXmlWsEnvironment jwsEnvironment) {
-        checkArgument(servletPath != null, "Servlet path is null");
+        checkArgument(nonNull(servletPath), "Servlet path is null");
         checkArgument(servletPath.startsWith("/"), "%s is not an absolute path", servletPath);
-        checkArgument(jwsEnvironment != null, "jwsEnvironment is null");
+        checkArgument(nonNull(jwsEnvironment), "jwsEnvironment is null");
         this.servletPath = servletPath.endsWith("/") ? servletPath + "*" : servletPath + "/*";
         this.jwsEnvironment = jwsEnvironment;
     }
@@ -57,15 +58,15 @@ public void initialize(Bootstrap<?> bootstrap) {
 
     @Override
     public void run(C configuration, Environment environment) {
-        checkArgument(environment != null, "Environment is null");
+        checkArgument(nonNull(environment), "Environment is null");
         environment.servlets().addServlet("CXF Servlet " + jwsEnvironment.getDefaultPath(),
                 jwsEnvironment.buildServlet()).addMapping(servletPath);
 
         environment.lifecycle().addServerLifecycleListener(
                 server -> jwsEnvironment.logEndpoints());
 
         var publishedEndpointUrlPrefix = getPublishedEndpointUrlPrefix(configuration);
-        if (publishedEndpointUrlPrefix != null) {
+        if (nonNull(publishedEndpointUrlPrefix)) {
             jwsEnvironment.setPublishedEndpointUrlPrefix(publishedEndpointUrlPrefix);
         }
     }
@@ -77,7 +78,7 @@ public void run(C configuration, Environment environment) {
      * @return javax.xml.ws.Endpoint
      */
     public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
-        checkArgument(endpointBuilder != null, "EndpointBuilder is null");
+        checkArgument(nonNull(endpointBuilder), "EndpointBuilder is null");
         return this.jwsEnvironment.publishEndpoint(endpointBuilder);
     }
 
@@ -89,7 +90,7 @@ public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
      * @return Jakarta XML Web Services client proxy.
      */
     public <T> T getClient(ClientBuilder<T> clientBuilder) {
-        checkArgument(clientBuilder != null, "ClientBuilder is null");
+        checkArgument(nonNull(clientBuilder), "ClientBuilder is null");
         return jwsEnvironment.getClient(clientBuilder);
     }
 

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/JakartaXmlWsEnvironment.java

@@ -1,6 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.nonNull;
 
 import jakarta.servlet.http.HttpServlet;
 import jakarta.validation.Validation;
@@ -99,12 +100,12 @@ public void logEndpoints() {
      * to allow further customization.
      */
     public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
-        checkArgument(endpointBuilder != null, "EndpointBuilder is null");
+        checkArgument(nonNull(endpointBuilder), "EndpointBuilder is null");
 
         var cxfEndpoint = new EndpointImpl(bus, endpointBuilder.getService());
-        if (endpointBuilder.publishedEndpointUrl() != null) {
+        if (nonNull(endpointBuilder.publishedEndpointUrl())) {
             cxfEndpoint.setPublishedEndpointUrl(endpointBuilder.publishedEndpointUrl());
-        } else if (publishedEndpointUrlPrefix != null) {
+        } else if (nonNull(publishedEndpointUrlPrefix)) {
             cxfEndpoint.setPublishedEndpointUrl(publishedEndpointUrlPrefix + endpointBuilder.getPath());
         }
         cxfEndpoint.publish(endpointBuilder.getPath());
@@ -120,7 +121,7 @@ public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
         var validatorFactory = Validation.buildDefaultValidatorFactory();
         invoker = this.createValidatingInvoker(invoker, validatorFactory.getValidator());
 
-        if (endpointBuilder.getSessionFactory() != null) {
+        if (nonNull(endpointBuilder.getSessionFactory())) {
             // Add invoker to handle UnitOfWork annotations. Note that this invoker is set up before
             // instrumented invoker(s) in order for instrumented invoker(s) to wrap "unit of work" invoker.
             invoker = unitOfWorkInvokerBuilder.create(
@@ -132,7 +133,7 @@ public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
         invoker = instrumentedInvokerBuilder.create(endpointBuilder.getService(), invoker);
         cxfEndpoint.getService().setInvoker(invoker);
 
-        if (endpointBuilder.getAuthentication() != null) {
+        if (nonNull(endpointBuilder.getAuthentication())) {
             // Configure CXF in interceptor to handle basic authentication
             var basicAuthInterceptor = this.createBasicAuthenticationInterceptor();
             basicAuthInterceptor.setAuthenticator(endpointBuilder.getAuthentication());
@@ -141,23 +142,23 @@ public EndpointImpl publishEndpoint(EndpointBuilder endpointBuilder) {
 
         // CXF interceptors
 
-        if (endpointBuilder.getCxfInInterceptors() != null) {
+        if (nonNull(endpointBuilder.getCxfInInterceptors())) {
             cxfEndpoint.getInInterceptors().addAll(endpointBuilder.getCxfInInterceptors());
         }
 
-        if (endpointBuilder.getCxfInFaultInterceptors() != null) {
+        if (nonNull(endpointBuilder.getCxfInFaultInterceptors())) {
             cxfEndpoint.getInFaultInterceptors().addAll(endpointBuilder.getCxfInFaultInterceptors());
         }
 
-        if (endpointBuilder.getCxfOutInterceptors() != null) {
+        if (nonNull(endpointBuilder.getCxfOutInterceptors())) {
             cxfEndpoint.getOutInterceptors().addAll(endpointBuilder.getCxfOutInterceptors());
         }
 
-        if (endpointBuilder.getCxfOutFaultInterceptors() != null) {
+        if (nonNull(endpointBuilder.getCxfOutFaultInterceptors())) {
             cxfEndpoint.getOutFaultInterceptors().addAll(endpointBuilder.getCxfOutFaultInterceptors());
         }
 
-        if (endpointBuilder.getProperties() != null) {
+        if (nonNull(endpointBuilder.getProperties())) {
             cxfEndpoint.getProperties().putAll(
                     endpointBuilder.getProperties());
         }
@@ -179,28 +180,28 @@ public <T> T getClient(ClientBuilder<T> clientBuilder) {
         proxyFactory.setAddress(clientBuilder.getAddress());
 
         // Jakarta XML Web Services handlers
-        if (clientBuilder.getHandlers() != null) {
+        if (nonNull(clientBuilder.getHandlers())) {
             for (var h : clientBuilder.getHandlers()) {
                 proxyFactory.getHandlers().add(h);
             }
         }
 
         // ClientProxyFactoryBean bindingId
-        if (clientBuilder.getBindingId() != null) {
+        if (nonNull(clientBuilder.getBindingId())) {
             proxyFactory.setBindingId(clientBuilder.getBindingId());
         }
 
         // CXF interceptors
-        if (clientBuilder.getCxfInInterceptors() != null) {
+        if (nonNull(clientBuilder.getCxfInInterceptors())) {
             proxyFactory.getInInterceptors().addAll(clientBuilder.getCxfInInterceptors());
         }
-        if (clientBuilder.getCxfInFaultInterceptors() != null) {
+        if (nonNull(clientBuilder.getCxfInFaultInterceptors())) {
             proxyFactory.getInFaultInterceptors().addAll(clientBuilder.getCxfInFaultInterceptors());
         }
-        if (clientBuilder.getCxfOutInterceptors() != null) {
+        if (nonNull(clientBuilder.getCxfOutInterceptors())) {
             proxyFactory.getOutInterceptors().addAll(clientBuilder.getCxfOutInterceptors());
         }
-        if (clientBuilder.getCxfOutFaultInterceptors() != null) {
+        if (nonNull(clientBuilder.getCxfOutFaultInterceptors())) {
             proxyFactory.getOutFaultInterceptors().addAll(clientBuilder.getCxfOutFaultInterceptors());
         }
 

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/UnitOfWorkInvoker.java

@@ -1,5 +1,6 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
+import static java.util.Objects.nonNull;
 import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableMap;
@@ -96,7 +97,7 @@ private void configureSession(Session session, UnitOfWork unitOfWork) {
     private void rollbackTransaction(Session session, UnitOfWork unitOfWork) {
         if (unitOfWork.transactional()) {
             var txn = session.getTransaction();
-            if (txn != null && txn.getStatus().equals(TransactionStatus.ACTIVE)) {
+            if (nonNull(txn) && txn.getStatus().equals(TransactionStatus.ACTIVE)) {
                 txn.rollback();
             }
         }
@@ -109,7 +110,7 @@ private void rollbackTransaction(Session session, UnitOfWork unitOfWork) {
     private void commitTransaction(Session session, UnitOfWork unitOfWork) {
         if (unitOfWork.transactional()) {
             var txn = session.getTransaction();
-            if (txn != null && txn.getStatus().equals(TransactionStatus.ACTIVE)) {
+            if (nonNull(txn) && txn.getStatus().equals(TransactionStatus.ACTIVE)) {
                 txn.commit();
             }
         }

dropwizard-jakarta-xml-ws/src/main/java/org/kiwiproject/dropwizard/jakarta/xml/ws/ValidatingInvoker.java

@@ -1,5 +1,7 @@
 package org.kiwiproject.dropwizard.jakarta.xml.ws;
 
+import static java.util.Objects.nonNull;
+
 import io.dropwizard.validation.ConstraintViolations;
 import io.dropwizard.validation.Validated;
 import jakarta.validation.Valid;
@@ -43,13 +45,13 @@ public Object invoke(Exchange exchange, Object o) {
         List<Object> params = null;
         if (o instanceof List) {
             params = CastUtils.cast((List<?>) o);
-        } else if (o != null) {
+        } else if (nonNull(o)) {
             params = new MessageContentsList(o);
         }
         /* Get actual parameter list end */
 
         // validate each parameter in the list
-        if (params != null) {
+        if (nonNull(params)) {
             var i = 0;
             try {
                 for (var parameter : params) {
@@ -79,7 +81,7 @@ public Object invoke(Exchange exchange, Object o) {
     private Object validate(Annotation[] annotations, Object value) {
         var classes = findValidationGroups(annotations);
 
-        if (classes != null && classes.length > 0) {
+        if (nonNull(classes) && classes.length > 0) {
             var errors = ConstraintViolations.format(validator.validate(value, classes));
             if (errors.isEmpty()) {
                 return value;