Nullability fine-tuning around declaration inconsistencies

Issue: SPR-15720
Issue: SPR-15792

spring-websocket/src/main/java/org/springframework/web/socket/adapter/standard/StandardWebSocketSession.java

@@ -144,11 +144,13 @@ public class StandardWebSocketSession extends AbstractWebSocketSession<Session>
 	}
 
 	@Override
+	@Nullable
 	public InetSocketAddress getLocalAddress() {
 		return this.localAddress;
 	}
 
 	@Override
+	@Nullable
 	public InetSocketAddress getRemoteAddress() {
 		return this.remoteAddress;
 	}

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketTransportRegistration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.web.socket.config.annotation;
 
+package org.springframework.web.socket.config.annotation;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -31,10 +31,13 @@ import org.springframework.web.socket.handler.WebSocketHandlerDecoratorFactory;
  */
 public class WebSocketTransportRegistration {
 
+	@Nullable
 	private Integer messageSizeLimit;
 
+	@Nullable
 	private Integer sendTimeLimit;
 
+	@Nullable
 	private Integer sendBufferSizeLimit;
 
 	private final List<WebSocketHandlerDecoratorFactory> decoratorFactories = new ArrayList<>(2);

spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java

@@ -218,17 +218,17 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		@Override
 		public boolean equals(Object other) {
 			return (this == other ||
-					(other instanceof SimpUser && this.name.equals(((SimpUser) other).getName())));
+					(other instanceof SimpUser && getName().equals(((SimpUser) other).getName())));
 		}
 
 		@Override
 		public int hashCode() {
-			return this.name.hashCode();
+			return getName().hashCode();
 		}
 
 		@Override
 		public String toString() {
-			return "name=" + this.name + ", sessions=" + this.userSessions;
+			return "name=" + getName() + ", sessions=" + this.userSessions;
 		}
 	}
 
@@ -274,17 +274,17 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		@Override
 		public boolean equals(Object other) {
 			return (this == other ||
-					(other instanceof SimpSubscription && this.id.equals(((SimpSubscription) other).getId())));
+					(other instanceof SimpSubscription && getId().equals(((SimpSubscription) other).getId())));
 		}
 
 		@Override
 		public int hashCode() {
-			return this.id.hashCode();
+			return getId().hashCode();
 		}
 
 		@Override
 		public String toString() {
-			return "id=" + this.id + ", subscriptions=" + this.subscriptions;
+			return "id=" + getId() + ", subscriptions=" + this.subscriptions;
 		}
 	}
 
@@ -330,13 +330,13 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 				return false;
 			}
 			SimpSubscription otherSubscription = (SimpSubscription) other;
-			return (this.id.equals(otherSubscription.getId()) &&
+			return (getId().equals(otherSubscription.getId()) &&
 					getSession().getId().equals(otherSubscription.getSession().getId()));
 		}
 
 		@Override
 		public int hashCode() {
-			return this.id.hashCode() * 31 + getSession().getId().hashCode();
+			return getId().hashCode() * 31 + getSession().getId().hashCode();
 		}
 
 		@Override

spring-websocket/src/main/java/org/springframework/web/socket/messaging/WebSocketStompClient.java

@@ -111,7 +111,7 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 	 * property to "10000,10000" if it is currently set to "0,0".
 	 */
 	@Override
-	public void setTaskScheduler(TaskScheduler taskScheduler) {
+	public void setTaskScheduler(@Nullable TaskScheduler taskScheduler) {
 		if (!isDefaultHeartbeatEnabled()) {
 			setDefaultHeartbeat(new long[] {10000, 10000});
 		}
@@ -296,6 +296,7 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 
 		private final StompWebSocketMessageCodec codec = new StompWebSocketMessageCodec(getInboundMessageSizeLimit());
 
+		@Nullable
 		private volatile WebSocketSession session;
 
 		private volatile long lastReadTime = -1;
@@ -312,7 +313,7 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 		// ListenableFutureCallback implementation: handshake outcome
 
 		@Override
-		public void onSuccess(WebSocketSession webSocketSession) {
+		public void onSuccess(@Nullable WebSocketSession webSocketSession) {
 		}
 
 		@Override
@@ -381,7 +382,9 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 			updateLastWriteTime();
 			SettableListenableFuture<Void> future = new SettableListenableFuture<>();
 			try {
-				this.session.sendMessage(this.codec.encode(message, this.session.getClass()));
+				WebSocketSession session = this.session;
+				Assert.state(session != null, "No WebSocketSession available");
+				session.sendMessage(this.codec.encode(message, session.getClass()));
 				future.set(null);
 			}
 			catch (Throwable ex) {
@@ -438,12 +441,15 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 
 		@Override
 		public void close() {
-			try {
-				this.session.close();
-			}
-			catch (IOException ex) {
-				if (logger.isDebugEnabled()) {
-					logger.debug("Failed to close session: " + this.session.getId(), ex);
+			WebSocketSession session = this.session;
+			if (session != null) {
+				try {
+					session.close();
+				}
+				catch (IOException ex) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Failed to close session: " + session.getId(), ex);
+					}
 				}
 			}
 		}

spring-websocket/src/main/java/org/springframework/web/socket/server/support/HttpSessionHandshakeInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -172,7 +172,7 @@ public class HttpSessionHandshakeInterceptor implements HandshakeInterceptor {
 
 	@Override
 	public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response,
-			WebSocketHandler wsHandler, Exception ex) {
+			WebSocketHandler wsHandler, @Nullable Exception ex) {
 	}
 
 }

spring-websocket/src/main/java/org/springframework/web/socket/server/support/OriginHandshakeInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -28,6 +28,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.server.ServerHttpRequest;
 import org.springframework.http.server.ServerHttpResponse;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.socket.WebSocketHandler;
 import org.springframework.web.socket.server.HandshakeInterceptor;
@@ -103,7 +104,7 @@ public class OriginHandshakeInterceptor implements HandshakeInterceptor {
 
 	@Override
 	public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response,
-			WebSocketHandler wsHandler, Exception exception) {
+			WebSocketHandler wsHandler, @Nullable Exception exception) {
 	}
 
 }

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/DefaultTransportRequest.java

@@ -117,6 +117,7 @@ class DefaultTransportRequest implements TransportRequest {
 	}
 
 	@Override
+	@Nullable
 	public Principal getUser() {
 		return this.user;
 	}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/WebSocketTransport.java

@@ -25,6 +25,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.context.Lifecycle;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.concurrent.ListenableFuture;
 import org.springframework.util.concurrent.ListenableFutureCallback;
@@ -87,7 +88,7 @@ public class WebSocketTransport implements Transport, Lifecycle {
 		this.webSocketClient.doHandshake(handler, headers, url).addCallback(
 				new ListenableFutureCallback<WebSocketSession>() {
 					@Override
-					public void onSuccess(WebSocketSession webSocketSession) {
+					public void onSuccess(@Nullable WebSocketSession webSocketSession) {
 						// WebSocket session ready, SockJS Session not yet
 					}
 					@Override

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/AbstractTransportHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -19,6 +19,8 @@ package org.springframework.web.socket.sockjs.transport.handler;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.web.socket.sockjs.transport.SockJsServiceConfig;
 import org.springframework.web.socket.sockjs.transport.TransportHandler;
 
@@ -32,6 +34,7 @@ public abstract class AbstractTransportHandler implements TransportHandler {
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private SockJsServiceConfig serviceConfig;
 
 
@@ -41,6 +44,7 @@ public abstract class AbstractTransportHandler implements TransportHandler {
 	}
 
 	public SockJsServiceConfig getServiceConfig() {
+		Assert.state(this.serviceConfig != null, "No SockJsServiceConfig available");
 		return this.serviceConfig;
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractHttpSockJsSession.java

@@ -107,16 +107,19 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 	}
 
 	@Override
+	@Nullable
 	public Principal getPrincipal() {
 		return this.principal;
 	}
 
 	@Override
+	@Nullable
 	public InetSocketAddress getLocalAddress() {
 		return this.localAddress;
 	}
 
 	@Override
+	@Nullable
 	public InetSocketAddress getRemoteAddress() {
 		return this.remoteAddress;
 	}
@@ -127,13 +130,14 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 	 * the selected protocol set through this setter.
 	 * @param protocol the sub-protocol to set
 	 */
-	public void setAcceptedProtocol(String protocol) {
+	public void setAcceptedProtocol(@Nullable String protocol) {
 		this.acceptedProtocol = protocol;
 	}
 
 	/**
 	 * Return the selected sub-protocol to use.
 	 */
+	@Nullable
 	public String getAcceptedProtocol() {
 		return this.acceptedProtocol;
 	}