Fix Sonar smells for websocket module

* Introduce `JavaUtils` for chaining properties setting
* Fix method complexity in the `ServerWebSocketContainer` using newly
introduced `JavaUtils`
* Make `JavaUtils` as `final`

spring-integration-core/src/main/java/org/springframework/integration/util/JavaUtils.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.util;
+
+import java.util.function.Consumer;
+
+/**
+ * Chained utility methods to simplify some Java repetitive code. Obtain a reference to
+ * the singleton {@link #INSTANCE} and then chain calls to the utility methods.
+ *
+ * @author Gary Russell
+ * @author Artem Bilan
+ *
+ * @since 5.1.3
+ */
+public final class JavaUtils {
+
+	/**
+	 * The singleton instance of this utility class.
+	 */
+	public static final JavaUtils INSTANCE = new JavaUtils();
+
+	private JavaUtils() {
+		super();
+	}
+
+	/**
+	 * Invoke {@link Consumer#accept(Object)} with the value if the condition is true.
+	 * @param condition the condition.
+	 * @param value the value.
+	 * @param consumer the consumer.
+	 * @param <T> the value type.
+	 * @return this.
+	 */
+	public <T> JavaUtils acceptIfCondition(boolean condition, T value, Consumer<T> consumer) {
+		if (condition) {
+			consumer.accept(value);
+		}
+		return this;
+	}
+
+	/**
+	 * Invoke {@link Consumer#accept(Object)} with the value if it is not null.
+	 * @param value the value.
+	 * @param consumer the consumer.
+	 * @param <T> the value type.
+	 * @return this.
+	 */
+	public <T> JavaUtils acceptIfNotNull(T value, Consumer<T> consumer) {
+		if (value != null) {
+			consumer.accept(value);
+		}
+		return this;
+	}
+
+}

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/ClientWebSocketContainer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2017 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,6 +46,7 @@ import org.springframework.web.socket.client.WebSocketClient;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ *
  * @since 4.1
  */
 public final class ClientWebSocketContainer extends IntegrationWebSocketContainer implements SmartLifecycle {
@@ -221,7 +222,7 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 		}
 
 		@Override
-		public void stopInternal() throws Exception {
+		public void stopInternal() throws Exception { // NOSONAR honor super
 			if (this.syncClientLifecycle) {
 				((Lifecycle) this.client).stop();
 			}
@@ -236,7 +237,9 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 
 		@Override
 		protected void openConnection() {
-			logger.info("Connecting to WebSocket at " + getUri());
+			if (logger.isInfoEnabled()) {
+				logger.info("Connecting to WebSocket at " + getUri());
+			}
 			ClientWebSocketContainer.this.headers.setSecWebSocketProtocol(getSubProtocols());
 			ListenableFuture<WebSocketSession> future =
 					this.client.doHandshake(ClientWebSocketContainer.this.webSocketHandler,
@@ -262,10 +265,9 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 		}
 
 		@Override
-		protected void closeConnection() throws Exception {
+		protected void closeConnection() throws Exception { // NOSONAR
 			if (ClientWebSocketContainer.this.clientSession != null) {
-				ClientWebSocketContainer.this.closeSession(ClientWebSocketContainer.this.clientSession,
-						CloseStatus.NORMAL);
+				closeSession(ClientWebSocketContainer.this.clientSession, CloseStatus.NORMAL);
 			}
 		}
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/IntegrationWebSocketContainer.java

@@ -27,6 +27,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.web.socket.CloseStatus;
 import org.springframework.web.socket.SubProtocolCapable;
 import org.springframework.web.socket.WebSocketHandler;
@@ -52,25 +53,31 @@ import org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorato
  *
  * @author Artem Bilan
  * @author Gary Russell
+ *
  * @since 4.1
+ *
  * @see org.springframework.integration.websocket.inbound.WebSocketInboundChannelAdapter
  * @see org.springframework.integration.websocket.outbound.WebSocketOutboundMessageHandler
  */
 public abstract class IntegrationWebSocketContainer implements DisposableBean {
 
-	protected final Log logger = LogFactory.getLog(this.getClass());
+	public static final int DEFAULT_SEND_TIME_LIMIT = 10 * 1000;
 
-	protected final WebSocketHandler webSocketHandler = new IntegrationWebSocketHandler();
+	public static final int DEFAULT_SEND_BUFFER_SIZE = 512 * 1024;
 
-	protected final Map<String, WebSocketSession> sessions = new ConcurrentHashMap<String, WebSocketSession>();
+	protected final Log logger = LogFactory.getLog(getClass()); // NOSONAR
 
-	private final List<String> supportedProtocols = new ArrayList<String>();
+	protected final WebSocketHandler webSocketHandler = new IntegrationWebSocketHandler(); // NOSONAR
+
+	protected final Map<String, WebSocketSession> sessions = new ConcurrentHashMap<>(); // NOSONAR
+
+	private final List<String> supportedProtocols = new ArrayList<>();
 
 	private volatile WebSocketListener messageListener;
 
-	private volatile int sendTimeLimit = 10 * 1000;
+	private volatile int sendTimeLimit = DEFAULT_SEND_TIME_LIMIT;
 
-	private volatile int sendBufferSizeLimit = 512 * 1024;
+	private volatile int sendBufferSizeLimit = DEFAULT_SEND_BUFFER_SIZE;
 
 	public void setSendTimeLimit(int sendTimeLimit) {
 		this.sendTimeLimit = sendTimeLimit;
@@ -98,7 +105,7 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 	}
 
 	public List<String> getSubProtocols() {
-		List<String> protocols = new ArrayList<String>();
+		List<String> protocols = new ArrayList<>();
 		if (this.messageListener != null) {
 			protocols.addAll(this.messageListener.getSubProtocols());
 		}
@@ -116,14 +123,16 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 		return session;
 	}
 
-	public void closeSession(WebSocketSession session, CloseStatus closeStatus) throws Exception {
+	public void closeSession(WebSocketSession session, CloseStatus closeStatus)
+			throws Exception { // NOSONAR
+
 		// Session may be unresponsive so clear first
 		session.close(closeStatus);
 		this.webSocketHandler.afterConnectionClosed(session, closeStatus);
 	}
 
 	@Override
-	public void destroy() throws Exception {
+	public void destroy() {
 		try {
 			// Notify sessions to stop flushing messages
 			for (WebSocketSession session : this.sessions.values()) {
@@ -159,15 +168,19 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 		}
 
 		@Override
-		public void afterConnectionEstablished(WebSocketSession sessionToDecorate) throws Exception { // NOSONAR SF ifce
-			WebSocketSession session = new ConcurrentWebSocketSessionDecorator(sessionToDecorate,
-					IntegrationWebSocketContainer.this.sendTimeLimit,
-					IntegrationWebSocketContainer.this.sendBufferSizeLimit);
+		public void afterConnectionEstablished(WebSocketSession sessionToDecorate)
+				throws Exception { // NOSONAR
+
+			WebSocketSession session =
+					new ConcurrentWebSocketSessionDecorator(sessionToDecorate,
+							IntegrationWebSocketContainer.this.sendTimeLimit,
+							IntegrationWebSocketContainer.this.sendBufferSizeLimit);
 
 			IntegrationWebSocketContainer.this.sessions.put(session.getId(), session);
 			if (IntegrationWebSocketContainer.this.logger.isDebugEnabled()) {
-				IntegrationWebSocketContainer.this.logger.debug("Started WebSocket session = " + session.getId() + ", number of sessions = "
-						+ IntegrationWebSocketContainer.this.sessions.size());
+				IntegrationWebSocketContainer.this.logger.debug("Started WebSocket session = " 	+
+						session.getId() + ", number of sessions = "	+
+						IntegrationWebSocketContainer.this.sessions.size());
 			}
 			if (IntegrationWebSocketContainer.this.messageListener != null) {
 				IntegrationWebSocketContainer.this.messageListener.afterSessionStarted(session);
@@ -175,29 +188,34 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 		}
 
 		@Override
-		public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {
+		public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus)
+				throws Exception { // NOSONAR
+
 			WebSocketSession removed = IntegrationWebSocketContainer.this.sessions.remove(session.getId());
-			if (removed != null) {
-				if (IntegrationWebSocketContainer.this.messageListener != null) {
-					IntegrationWebSocketContainer.this.messageListener.afterSessionEnded(session, closeStatus);
-				}
+			if (removed != null && IntegrationWebSocketContainer.this.messageListener != null) {
+				IntegrationWebSocketContainer.this.messageListener.afterSessionEnded(session, closeStatus);
 			}
 		}
 
 		@Override
-		public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
+		public void handleTransportError(WebSocketSession session, Throwable exception)
+				throws Exception { // NOSONAR
+
 			IntegrationWebSocketContainer.this.sessions.remove(session.getId());
-			throw new Exception(exception);
+			ReflectionUtils.rethrowException(exception);
 		}
 
 		@Override
-		public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {
+		public void handleMessage(WebSocketSession session, WebSocketMessage<?> message)
+				throws Exception { // NOSONAR
+
 			if (IntegrationWebSocketContainer.this.messageListener != null) {
 				IntegrationWebSocketContainer.this.messageListener.onMessage(session, message);
 			}
 			else if (IntegrationWebSocketContainer.this.logger.isInfoEnabled()) {
-				IntegrationWebSocketContainer.this.logger.info("This 'WebSocketHandlerContainer' isn't configured with 'WebSocketMessageListener'."
-						+ " Received messages are ignored. Current message is: " + message);
+				IntegrationWebSocketContainer.this.logger.info("This 'WebSocketHandlerContainer' isn't " +
+						"configured with 'WebSocketMessageListener'." +
+						" Received messages are ignored. Current message is: " + message);
 			}
 		}
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/ServerWebSocketContainer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Arrays;
 
 import org.springframework.context.Lifecycle;
 import org.springframework.context.SmartLifecycle;
+import org.springframework.integration.util.JavaUtils;
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -46,6 +47,7 @@ import org.springframework.web.socket.sockjs.transport.TransportHandler;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ *
  * @since 4.1
  */
 public class ServerWebSocketContainer extends IntegrationWebSocketContainer
@@ -142,47 +144,38 @@ public class ServerWebSocketContainer extends IntegrationWebSocketContainer
 				.addInterceptors(this.interceptors)
 				.setAllowedOrigins(this.origins);
 
+		configureSockJsOptionsIfAny(registration);
+	}
+
+	private void configureSockJsOptionsIfAny(WebSocketHandlerRegistration registration) {
 		if (this.sockJsServiceOptions != null) {
 			SockJsServiceRegistration sockJsServiceRegistration = registration.withSockJS();
-			if (this.sockJsServiceOptions.webSocketEnabled != null) {
-				sockJsServiceRegistration.setWebSocketEnabled(this.sockJsServiceOptions.webSocketEnabled);
-			}
-			if (this.sockJsServiceOptions.clientLibraryUrl != null) {
-				sockJsServiceRegistration.setClientLibraryUrl(this.sockJsServiceOptions.clientLibraryUrl);
-			}
-			if (this.sockJsServiceOptions.disconnectDelay != null) {
-				sockJsServiceRegistration.setDisconnectDelay(this.sockJsServiceOptions.disconnectDelay);
-			}
-			if (this.sockJsServiceOptions.heartbeatTime != null) {
-				sockJsServiceRegistration.setHeartbeatTime(this.sockJsServiceOptions.heartbeatTime);
-			}
-			if (this.sockJsServiceOptions.httpMessageCacheSize != null) {
-				sockJsServiceRegistration.setHttpMessageCacheSize(this.sockJsServiceOptions.httpMessageCacheSize);
-			}
-			if (this.sockJsServiceOptions.heartbeatTime != null) {
-				sockJsServiceRegistration.setHeartbeatTime(this.sockJsServiceOptions.heartbeatTime);
-			}
-			if (this.sockJsServiceOptions.sessionCookieNeeded != null) {
-				sockJsServiceRegistration.setSessionCookieNeeded(this.sockJsServiceOptions.sessionCookieNeeded);
-			}
-			if (this.sockJsServiceOptions.streamBytesLimit != null) {
-				sockJsServiceRegistration.setStreamBytesLimit(this.sockJsServiceOptions.streamBytesLimit);
-			}
-			if (this.sockJsServiceOptions.transportHandlers != null) {
-				sockJsServiceRegistration.setTransportHandlers(this.sockJsServiceOptions.transportHandlers);
-			}
-			if (this.sockJsServiceOptions.taskScheduler != null) {
-				sockJsServiceRegistration.setTaskScheduler(this.sockJsServiceOptions.taskScheduler);
-			}
-			if (this.sockJsServiceOptions.messageCodec != null) {
-				sockJsServiceRegistration.setMessageCodec(this.sockJsServiceOptions.messageCodec);
-			}
-			if (this.sockJsServiceOptions.suppressCors != null) {
-				sockJsServiceRegistration.setSupressCors(this.sockJsServiceOptions.suppressCors);
-			}
-
+			JavaUtils.INSTANCE
+					.acceptIfNotNull(this.sockJsServiceOptions.webSocketEnabled,
+							sockJsServiceRegistration::setWebSocketEnabled)
+					.acceptIfNotNull(this.sockJsServiceOptions.clientLibraryUrl,
+							sockJsServiceRegistration::setClientLibraryUrl)
+					.acceptIfNotNull(this.sockJsServiceOptions.disconnectDelay,
+							sockJsServiceRegistration::setDisconnectDelay)
+					.acceptIfNotNull(this.sockJsServiceOptions.heartbeatTime,
+							sockJsServiceRegistration::setHeartbeatTime)
+					.acceptIfNotNull(this.sockJsServiceOptions.httpMessageCacheSize,
+							sockJsServiceRegistration::setHttpMessageCacheSize)
+					.acceptIfNotNull(this.sockJsServiceOptions.heartbeatTime,
+							sockJsServiceRegistration::setHeartbeatTime)
+					.acceptIfNotNull(this.sockJsServiceOptions.sessionCookieNeeded,
+							sockJsServiceRegistration::setSessionCookieNeeded)
+					.acceptIfNotNull(this.sockJsServiceOptions.streamBytesLimit,
+							sockJsServiceRegistration::setStreamBytesLimit)
+					.acceptIfNotNull(this.sockJsServiceOptions.transportHandlers,
+							sockJsServiceRegistration::setTransportHandlers)
+					.acceptIfNotNull(this.sockJsServiceOptions.taskScheduler,
+							sockJsServiceRegistration::setTaskScheduler)
+					.acceptIfNotNull(this.sockJsServiceOptions.messageCodec,
+							sockJsServiceRegistration::setMessageCodec)
+					.acceptIfNotNull(this.sockJsServiceOptions.suppressCors,
+							sockJsServiceRegistration::setSupressCors);
 		}
-
 	}
 
 	public void setAutoStartup(boolean autoStartup) {

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/WebSocketListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,9 @@ import org.springframework.web.socket.WebSocketSession;
  *
  * @author Andy Wilkinson
  * @author Artem Bilan
+ *
  * @since 4.1
+ *
  * @see org.springframework.integration.websocket.inbound.WebSocketInboundChannelAdapter
  */
 public interface WebSocketListener extends SubProtocolCapable {
@@ -42,14 +44,15 @@ public interface WebSocketListener extends SubProtocolCapable {
 	 * @param message the WebSocket message
 	 * @throws Exception the 'onMessage' Exception
 	 */
-	void onMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception;
+	void onMessage(WebSocketSession session, WebSocketMessage<?> message)
+			throws Exception; // NOSONAR Remove in 5.2
 
 	/**
 	 * Invoked after a {@link WebSocketSession} has started.
 	 * @param session the WebSocket session
 	 * @throws Exception the 'afterSessionStarted' Exception
 	 */
-	void afterSessionStarted(WebSocketSession session) throws Exception;
+	void afterSessionStarted(WebSocketSession session) throws Exception; // NOSONAR Remove in 5.2
 
 	/**
 	 * Invoked after a {@link WebSocketSession} has ended.
@@ -57,6 +60,7 @@ public interface WebSocketListener extends SubProtocolCapable {
 	 * @param closeStatus the reason why the session was closed
 	 * @throws Exception the 'afterSessionEnded' Exception
 	 */
-	void afterSessionEnded(WebSocketSession session, CloseStatus closeStatus) throws Exception;
+	void afterSessionEnded(WebSocketSession session, CloseStatus closeStatus)
+			throws Exception; // NOSONAR Remove in 5.2
 
 }

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/config/WebSocketIntegrationConfigurationInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,10 +49,9 @@ import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
  */
 public class WebSocketIntegrationConfigurationInitializer implements IntegrationConfigurationInitializer {
 
-	private static final Log logger = // NOSONAR lower case
-			LogFactory.getLog(WebSocketIntegrationConfigurationInitializer.class);
+	private static final Log LOGGER = LogFactory.getLog(WebSocketIntegrationConfigurationInitializer.class);
 
-	private static final boolean servletPresent = // NOSONAR lower case
+	private static final boolean SERVLET_PRESENT =
 			ClassUtils.isPresent("javax.servlet.Servlet",
 					WebSocketIntegrationConfigurationInitializer.class.getClassLoader());
 
@@ -64,7 +63,7 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 			this.registerEnableWebSocketIfNecessary((BeanDefinitionRegistry) beanFactory);
 		}
 		else {
-			logger.warn("'DelegatingWebSocketConfiguration' isn't registered because 'beanFactory'" +
+			LOGGER.warn("'DelegatingWebSocketConfiguration' isn't registered because 'beanFactory'" +
 					" isn't an instance of `BeanDefinitionRegistry`.");
 		}
 	}
@@ -86,7 +85,7 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 	 * applications when {@link org.springframework.integration.config.EnableIntegration} is in use.
 	 */
 	private void registerEnableWebSocketIfNecessary(BeanDefinitionRegistry registry) {
-		if (servletPresent) {
+		if (SERVLET_PRESENT) {
 			if (!registry.containsBeanDefinition("defaultSockJsTaskScheduler")) {
 				BeanDefinitionBuilder sockJsTaskSchedulerBuilder =
 						BeanDefinitionBuilder.genericBeanDefinition(ThreadPoolTaskScheduler.class)
@@ -156,13 +155,17 @@ public class WebSocketIntegrationConfigurationInitializer implements Integration
 
 	private static class IntegrationServletWebSocketHandlerRegistry extends ServletWebSocketHandlerRegistry {
 
+		IntegrationServletWebSocketHandlerRegistry() {
+			super();
+		}
+
 		@Override
-		public boolean requiresTaskScheduler() {
+		public boolean requiresTaskScheduler() { // NOSONAR visibility
 			return super.requiresTaskScheduler();
 		}
 
 		@Override
-		public void setTaskScheduler(TaskScheduler scheduler) {
+		public void setTaskScheduler(TaskScheduler scheduler) { // NOSONAR visibility
 			super.setTaskScheduler(scheduler);
 		}
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/outbound/WebSocketOutboundMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -136,7 +136,7 @@ public class WebSocketOutboundMessageHandler extends AbstractMessageHandler {
 	}
 
 	@Override
-	protected void handleMessageInternal(Message<?> message) throws Exception {
+	protected void handleMessageInternal(Message<?> message) throws Exception { // NOSONAR
 		String sessionId = null;
 		if (!this.client) {
 			sessionId = this.subProtocolHandlerRegistry.resolveSessionId(message);

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/support/PassThruSubProtocolHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,11 +41,12 @@ import org.springframework.web.socket.messaging.SubProtocolHandler;
  * on 'send' part and vise versa - on 'receive' part.
  *
  * @author Artem Bilan
+ *
  * @since 4.1
  */
 public class PassThruSubProtocolHandler implements SubProtocolHandler {
 
-	final List<String> supportedProtocols = new ArrayList<String>();
+	private final List<String> supportedProtocols = new ArrayList<>();
 
 	public void setSupportedProtocols(String... supportedProtocols) {
 		Assert.noNullElements(supportedProtocols, "'supportedProtocols' must not be empty");
@@ -59,7 +60,8 @@ public class PassThruSubProtocolHandler implements SubProtocolHandler {
 
 	@Override
 	public void handleMessageFromClient(WebSocketSession session, WebSocketMessage<?> webSocketMessage,
-			MessageChannel outputChannel) throws Exception {
+			MessageChannel outputChannel) {
+
 		SimpMessageHeaderAccessor headerAccessor = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE);
 		headerAccessor.setSessionId(session.getId());
 		headerAccessor.setSessionAttributes(session.getAttributes());
@@ -78,7 +80,9 @@ public class PassThruSubProtocolHandler implements SubProtocolHandler {
 	}
 
 	@Override
-	public void handleMessageToClient(WebSocketSession session, Message<?> message) throws Exception {
+	public void handleMessageToClient(WebSocketSession session, Message<?> message)
+			throws Exception { // NOSONAR
+
 		Object payload = message.getPayload();
 		if (payload instanceof String) {
 			session.sendMessage(new TextMessage((String) payload));
@@ -91,7 +95,7 @@ public class PassThruSubProtocolHandler implements SubProtocolHandler {
 		}
 		else {
 			throw new IllegalArgumentException("Unsupported payload type: " + payload.getClass()
-					+ ". Can be one of: " + Arrays.<Class<?>>asList(String.class, byte[].class, ByteBuffer.class));
+					+ ". Can be one of: " + Arrays.asList(String.class, byte[].class, ByteBuffer.class));
 		}
 	}
 
@@ -101,13 +105,12 @@ public class PassThruSubProtocolHandler implements SubProtocolHandler {
 	}
 
 	@Override
-	public void afterSessionStarted(WebSocketSession session, MessageChannel outputChannel) throws Exception {
+	public void afterSessionStarted(WebSocketSession session, MessageChannel outputChannel) {
 		// Subclasses might implement this method
 	}
 
 	@Override
-	public void afterSessionEnded(WebSocketSession session, CloseStatus closeStatus, MessageChannel outputChannel)
-			throws Exception {
+	public void afterSessionEnded(WebSocketSession session, CloseStatus closeStatus, MessageChannel outputChannel) {
 		// Subclasses might implement this method
 	}
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/support/SubProtocolHandlerRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2018 the original author or authors.
+ * Copyright 2014-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,9 +62,25 @@ public final class SubProtocolHandlerRegistry {
 
 	public SubProtocolHandlerRegistry(List<SubProtocolHandler> protocolHandlers,
 			SubProtocolHandler defaultProtocolHandler) {
+
 		Assert.state(!CollectionUtils.isEmpty(protocolHandlers) || defaultProtocolHandler != null,
 				"One of 'protocolHandlers' or 'defaultProtocolHandler' must be provided");
 
+		configureProtocolHandlers(protocolHandlers);
+
+		if (this.protocolHandlers.size() == 1 && defaultProtocolHandler == null) {
+			this.defaultProtocolHandler = this.protocolHandlers.values().iterator().next();
+		}
+		else {
+			this.defaultProtocolHandler = defaultProtocolHandler;
+			if (this.protocolHandlers.isEmpty() && this.defaultProtocolHandler != null) {
+				List<String> protocols = this.defaultProtocolHandler.getSupportedProtocols();
+				populateProtocolsForHandler(this.defaultProtocolHandler, protocols);
+			}
+		}
+	}
+
+	private void configureProtocolHandlers(List<SubProtocolHandler> protocolHandlers) {
 		if (!CollectionUtils.isEmpty(protocolHandlers)) {
 			for (SubProtocolHandler handler : protocolHandlers) {
 				List<String> protocols = handler.getSupportedProtocols();
@@ -74,30 +90,17 @@ public final class SubProtocolHandlerRegistry {
 					}
 					continue;
 				}
-				for (String protocol : protocols) {
-					SubProtocolHandler replaced = this.protocolHandlers.put(protocol, handler);
-					if (replaced != null) {
-						throw new IllegalStateException("Failed to map handler " + handler
-								+ " to protocol '" + protocol + "', it is already mapped to handler " + replaced);
-					}
-				}
+				populateProtocolsForHandler(handler, protocols);
 			}
 		}
+	}
 
-		if (this.protocolHandlers.size() == 1 && defaultProtocolHandler == null) {
-			this.defaultProtocolHandler = this.protocolHandlers.values().iterator().next();
-		}
-		else {
-			this.defaultProtocolHandler = defaultProtocolHandler;
-			if (this.protocolHandlers.isEmpty() && this.defaultProtocolHandler != null) {
-				List<String> protocols = this.defaultProtocolHandler.getSupportedProtocols();
-				for (String protocol : protocols) {
-					SubProtocolHandler replaced = this.protocolHandlers.put(protocol, this.defaultProtocolHandler);
-					if (replaced != null) {
-						throw new IllegalStateException("Failed to map handler " + this.defaultProtocolHandler
-								+ " to protocol '" + protocol + "', it is already mapped to handler " + replaced);
-					}
-				}
+	private void populateProtocolsForHandler(SubProtocolHandler handler, List<String> protocols) {
+		for (String protocol : protocols) {
+			SubProtocolHandler replaced = this.protocolHandlers.put(protocol, handler);
+			if (replaced != null) {
+				throw new IllegalStateException("Failed to map handler " + handler
+						+ " to protocol '" + protocol + "', it is already mapped to handler " + replaced);
 			}
 		}
 	}