New upstream version 4.3.4

12 files changed, 134 insertions, 164 deletions

diff --git a/spring-messaging/src/main/java/org/springframework/messaging/MessageChannel.java b/spring-messaging/src/main/java/org/springframework/messaging/MessageChannel.java
index f64ff0bf..d8712900 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/MessageChannel.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/MessageChannel.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -27,7 +27,7 @@ public interface MessageChannel {
 	/**
 	 * Constant for sending a message without a prescribed timeout.
 	 */
-	public static final long INDEFINITE_TIMEOUT = -1;
+	long INDEFINITE_TIMEOUT = -1;
 
 
 	/**
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java
index a388946f..e247cd9b 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java
@@ -73,10 +73,9 @@ public class MessageMethodArgumentResolver implements HandlerMethodArgumentResol
 		Class<?> targetPayloadType = getPayloadType(parameter);
 
 		if (!targetMessageType.isAssignableFrom(message.getClass())) {
-			String actual = ClassUtils.getQualifiedName(message.getClass());
-			String expected = ClassUtils.getQualifiedName(targetMessageType);
-			throw new MethodArgumentTypeMismatchException(message, parameter, "The actual message type " +
-					"[" + actual + "] does not match the expected type [" + expected + "]");
+			throw new MethodArgumentTypeMismatchException(message, parameter, "Actual message type '" +
+					ClassUtils.getDescriptiveType(message) + "' does not match expected type '" +
+					ClassUtils.getQualifiedName(targetMessageType) + "'");
 		}
 
 		Object payload = message.getPayload();
@@ -85,11 +84,9 @@ public class MessageMethodArgumentResolver implements HandlerMethodArgumentResol
 		}
 
 		if (isEmptyPayload(payload)) {
-			String actual = ClassUtils.getQualifiedName(payload.getClass());
-			String expected = ClassUtils.getQualifiedName(targetPayloadType);
-			throw new MessageConversionException(message, "Cannot convert from the " +
-					"expected payload type [" + expected + "] to the " +
-					"actual payload type [" + actual + "] when the payload is empty.");
+			throw new MessageConversionException(message, "Cannot convert from actual payload type '" +
+					ClassUtils.getDescriptiveType(payload) + "' to expected payload type '" +
+					ClassUtils.getQualifiedName(targetPayloadType) + "' when payload is empty");
 		}
 
 		payload = convertPayload(message, parameter, targetPayloadType);
@@ -132,10 +129,9 @@ public class MessageMethodArgumentResolver implements HandlerMethodArgumentResol
 		}
 
 		if (result == null) {
-			String actual = ClassUtils.getQualifiedName(targetPayloadType);
-			String expected = ClassUtils.getQualifiedName(message.getPayload().getClass());
-			throw new MessageConversionException(message, "No converter found to convert payload type [" +
-					actual + "] to expected payload type [" + expected + "]");
+			throw new MessageConversionException(message, "No converter found from actual payload type '" +
+					ClassUtils.getDescriptiveType(message.getPayload()) + "' to expected payload type '" +
+					ClassUtils.getQualifiedName(targetPayloadType) + "'");
 		}
 		return result;
 	}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java
index 82932ca8..584fa91a 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java
@@ -28,6 +28,7 @@ import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.ResolvableType;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.HandlerMethod;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -106,15 +107,13 @@ public class InvocableHandlerMethod extends HandlerMethod {
 	public Object invoke(Message<?> message, Object... providedArgs) throws Exception {
 		Object[] args = getMethodArgumentValues(message, providedArgs);
 		if (logger.isTraceEnabled()) {
-			StringBuilder sb = new StringBuilder("Invoking [");
-			sb.append(getBeanType().getSimpleName()).append(".");
-			sb.append(getMethod().getName()).append("] method with arguments ");
-			sb.append(Arrays.asList(args));
-			logger.trace(sb.toString());
+			logger.trace("Invoking '" + ClassUtils.getQualifiedMethodName(getMethod(), getBeanType()) +
+					"' with arguments " + Arrays.toString(args));
 		}
 		Object returnValue = doInvoke(args);
 		if (logger.isTraceEnabled()) {
-			logger.trace("Method [" + getMethod().getName() + "] returned [" + returnValue + "]");
+			logger.trace("Method [" + ClassUtils.getQualifiedMethodName(getMethod(), getBeanType()) +
+					"] returned [" + returnValue + "]");
 		}
 		return returnValue;
 	}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java
index dd473a26..5268d925 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java
@@ -133,13 +133,11 @@ public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueH
 
 	@Override
 	public boolean supportsReturnType(MethodParameter returnType) {
-		if (returnType.hasMethodAnnotation(SendTo.class) ||
+		return (returnType.hasMethodAnnotation(SendTo.class) ||
 				AnnotatedElementUtils.hasAnnotation(returnType.getDeclaringClass(), SendTo.class) ||
 				returnType.hasMethodAnnotation(SendToUser.class) ||
-				AnnotatedElementUtils.hasAnnotation(returnType.getDeclaringClass(), SendToUser.class)) {
-			return true;
-		}
-		return !this.annotationRequired;
+				AnnotatedElementUtils.hasAnnotation(returnType.getDeclaringClass(), SendToUser.class) ||
+				!this.annotationRequired);
 	}
 
 	@Override
@@ -188,56 +186,34 @@ public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueH
 	}
 
 	private Object findAnnotation(MethodParameter returnType) {
-		Annotation[] annot = new Annotation[4];
-		annot[0] = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendToUser.class);
-		annot[1] = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendTo.class);
-		annot[2] = AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendToUser.class);
-		annot[3] = AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendTo.class);
-
-		if (annot[0] != null && !ObjectUtils.isEmpty(((SendToUser) annot[0]).value())) {
-			return annot[0];
+		Annotation[] anns = new Annotation[4];
+		anns[0] = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendToUser.class);
+		anns[1] = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendTo.class);
+		anns[2] = AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendToUser.class);
+		anns[3] = AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendTo.class);
+
+		if (anns[0] != null && !ObjectUtils.isEmpty(((SendToUser) anns[0]).value())) {
+			return anns[0];
 		}
-		if (annot[1] != null && !ObjectUtils.isEmpty(((SendTo) annot[1]).value())) {
-			return annot[1];
+		if (anns[1] != null && !ObjectUtils.isEmpty(((SendTo) anns[1]).value())) {
+			return anns[1];
 		}
-		if (annot[2] != null && !ObjectUtils.isEmpty(((SendToUser) annot[2]).value())) {
-			return annot[2];
+		if (anns[2] != null && !ObjectUtils.isEmpty(((SendToUser) anns[2]).value())) {
+			return anns[2];
 		}
-		if (annot[3] != null && !ObjectUtils.isEmpty(((SendTo) annot[3]).value())) {
-			return annot[3];
+		if (anns[3] != null && !ObjectUtils.isEmpty(((SendTo) anns[3]).value())) {
+			return anns[3];
 		}
 
 		for (int i=0; i < 4; i++) {
-			if (annot[i] != null) {
-				return annot[i];
+			if (anns[i] != null) {
+				return anns[i];
 			}
 		}
 
 		return null;
 	}
 
-	private SendToUser getSendToUser(MethodParameter returnType) {
-		SendToUser annot = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendToUser.class);
-		if (annot != null && !ObjectUtils.isEmpty(annot.value())) {
-			return annot;
-		}
-		SendToUser typeAnnot = AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendToUser.class);
-		if (typeAnnot != null && !ObjectUtils.isEmpty(typeAnnot.value())) {
-			return typeAnnot;
-		}
-		return (annot != null ? annot : typeAnnot);
-	}
-
-	private SendTo getSendTo(MethodParameter returnType) {
-		SendTo sendTo = AnnotatedElementUtils.findMergedAnnotation(returnType.getMethod(), SendTo.class);
-		if (sendTo != null && !ObjectUtils.isEmpty(sendTo.value())) {
-			return sendTo;
-		}
-		else {
-			return AnnotatedElementUtils.findMergedAnnotation(returnType.getDeclaringClass(), SendTo.class);
-		}
-	}
-
 	@SuppressWarnings("unchecked")
 	private PlaceholderResolver initVarResolver(MessageHeaders headers) {
 		String name = DestinationVariableMethodArgumentResolver.DESTINATION_TEMPLATE_VARIABLES_HEADER;
@@ -268,7 +244,7 @@ public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueH
 		}
 
 		return (destination.startsWith("/") ?
-				new String[] {defaultPrefix + destination} : new String[] {defaultPrefix + "/" + destination});
+				new String[] {defaultPrefix + destination} : new String[] {defaultPrefix + '/' + destination});
 	}
 
 	private MessageHeaders createHeaders(String sessionId, MethodParameter returnType) {
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractBrokerRegistration.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractBrokerRegistration.java
index 93a25239..21f225eb 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractBrokerRegistration.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractBrokerRegistration.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -50,8 +50,8 @@ public abstract class AbstractBrokerRegistration {
 		this.clientInboundChannel = clientInboundChannel;
 		this.clientOutboundChannel = clientOutboundChannel;
 
-		this.destinationPrefixes = (destinationPrefixes != null)
-				? Arrays.<String>asList(destinationPrefixes) : Collections.<String>emptyList();
+		this.destinationPrefixes = (destinationPrefixes != null ?
+				Arrays.asList(destinationPrefixes) : Collections.<String>emptyList());
 	}
 
 
@@ -67,6 +67,7 @@ public abstract class AbstractBrokerRegistration {
 		return this.destinationPrefixes;
 	}
 
+
 	protected abstract AbstractBrokerMessageHandler getMessageHandler(SubscribableChannel brokerChannel);
 
 }
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/BufferingStompDecoder.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/BufferingStompDecoder.java
index bf521874..e31957e3 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/BufferingStompDecoder.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/BufferingStompDecoder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.messaging.simp.stomp;
 
-
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -28,7 +27,6 @@ import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 
-
 /**
  * An extension of {@link org.springframework.messaging.simp.stomp.StompDecoder}
  * that buffers content remaining in the input ByteBuffer after the parent
@@ -45,6 +43,7 @@ import org.springframework.util.MultiValueMap;
  *
  * @author Rossen Stoyanchev
  * @since 4.0.3
+ * @see StompDecoder
  */
 public class BufferingStompDecoder {
 
@@ -57,78 +56,57 @@ public class BufferingStompDecoder {
 	private volatile Integer expectedContentLength;
 
 
+	/**
+	 * Create a new {@code BufferingStompDecoder} wrapping the given {@code StompDecoder}.
+	 * @param stompDecoder the target decoder to wrap
+	 * @param bufferSizeLimit the buffer size limit
+	 */
 	public BufferingStompDecoder(StompDecoder stompDecoder, int bufferSizeLimit) {
-		Assert.notNull(stompDecoder, "'stompDecoder' is required");
-		Assert.isTrue(bufferSizeLimit > 0, "Buffer size must be greater than 0");
+		Assert.notNull(stompDecoder, "StompDecoder is required");
+		Assert.isTrue(bufferSizeLimit > 0, "Buffer size limit must be greater than 0");
 		this.stompDecoder = stompDecoder;
 		this.bufferSizeLimit = bufferSizeLimit;
 	}
 
 
 	/**
-	 * Return the wrapped
-	 * {@link org.springframework.messaging.simp.stomp.StompDecoder}.
+	 * Return the wrapped {@link StompDecoder}.
 	 */
-	public StompDecoder getStompDecoder() {
+	public final StompDecoder getStompDecoder() {
 		return this.stompDecoder;
 	}
 
 	/**
 	 * Return the configured buffer size limit.
 	 */
-	public int getBufferSizeLimit() {
+	public final int getBufferSizeLimit() {
 		return this.bufferSizeLimit;
 	}
 
-	/**
-	 * Calculate the current buffer size.
-	 */
-	public int getBufferSize() {
-		int size = 0;
-		for (ByteBuffer buffer : this.chunks) {
-			size = size + buffer.remaining();
-		}
-		return size;
-	}
-
-	/**
-	 * Get the expected content length of the currently buffered, incomplete STOMP frame.
-	 */
-	public Integer getExpectedContentLength() {
-		return this.expectedContentLength;
-	}
-
 
 	/**
 	 * Decodes one or more STOMP frames from the given {@code ByteBuffer} into a
 	 * list of {@link Message}s.
-	 *
 	 * <p>If there was enough data to parse a "content-length" header, then the
 	 * value is used to determine how much more data is needed before a new
 	 * attempt to decode is made.
-	 *
 	 * <p>If there was not enough data to parse the "content-length", or if there
 	 * is "content-length" header, every subsequent call to decode attempts to
 	 * parse again with all available data. Therefore the presence of a "content-length"
 	 * header helps to optimize the decoding of large messages.
-	 *
 	 * @param newBuffer a buffer containing new data to decode
-	 *
 	 * @return decoded messages or an empty list
 	 * @throws StompConversionException raised in case of decoding issues
 	 */
 	public List<Message<byte[]>> decode(ByteBuffer newBuffer) {
-
 		this.chunks.add(newBuffer);
-
 		checkBufferLimits();
 
-		if (getExpectedContentLength() != null && getBufferSize() < this.expectedContentLength) {
+		if (this.expectedContentLength != null && getBufferSize() < this.expectedContentLength) {
 			return Collections.<Message<byte[]>>emptyList();
 		}
 
 		ByteBuffer bufferToDecode = assembleChunksAndReset();
-
 		MultiValueMap<String, String> headers = new LinkedMultiValueMap<String, String>();
 		List<Message<byte[]>> messages = this.stompDecoder.decode(bufferToDecode, headers);
 
@@ -140,21 +118,6 @@ public class BufferingStompDecoder {
 		return messages;
 	}
 
-	private void checkBufferLimits() {
-		if (getExpectedContentLength() != null) {
-			if (getExpectedContentLength() > getBufferSizeLimit()) {
-				throw new StompConversionException(
-						"The 'content-length' header " + getExpectedContentLength() +
-								"  exceeds the configured message buffer size limit " + getBufferSizeLimit());
-			}
-		}
-		if (getBufferSize() > getBufferSizeLimit()) {
-			throw new StompConversionException("The configured stomp frame buffer size limit of " +
-					getBufferSizeLimit() + " bytes has been exceeded");
-
-		}
-	}
-
 	private ByteBuffer assembleChunksAndReset() {
 		ByteBuffer result;
 		if (this.chunks.size() == 1) {
@@ -172,4 +135,36 @@ public class BufferingStompDecoder {
 		return result;
 	}
 
+	private void checkBufferLimits() {
+		if (this.expectedContentLength != null) {
+			if (this.expectedContentLength > this.bufferSizeLimit) {
+				throw new StompConversionException(
+						"STOMP 'content-length' header value " + this.expectedContentLength +
+						"  exceeds configured buffer size limit " + this.bufferSizeLimit);
+			}
+		}
+		if (getBufferSize() > this.bufferSizeLimit) {
+			throw new StompConversionException("The configured STOMP buffer size limit of " +
+					this.bufferSizeLimit + " bytes has been exceeded");
+		}
+	}
+
+	/**
+	 * Calculate the current buffer size.
+	 */
+	public int getBufferSize() {
+		int size = 0;
+		for (ByteBuffer buffer : this.chunks) {
+			size = size + buffer.remaining();
+		}
+		return size;
+	}
+
+	/**
+	 * Get the expected content length of the currently buffered, incomplete STOMP frame.
+	 */
+	public Integer getExpectedContentLength() {
+		return this.expectedContentLength;
+	}
+
 }
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
index e56b2a37..708f277b 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompClientSupport.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -26,15 +26,14 @@ import org.springframework.util.Assert;
 /**
  * Base class for STOMP client implementations.
  *
- * <p>Subclasses can connect over WebSocket or TCP using any library.
- * When creating a new connection a sub-class can create an instance of
- * {@link DefaultStompSession} which extends
- * {@link org.springframework.messaging.tcp.TcpConnectionHandler
- * TcpConnectionHandler} whose lifecycle methods the sub-class must then invoke.
+ * <p>Subclasses can connect over WebSocket or TCP using any library. When creating
+ * a new connection, a subclass can create an instance of @link DefaultStompSession}
+ * which extends {@link org.springframework.messaging.tcp.TcpConnectionHandler}
+ * whose lifecycle methods the subclass must then invoke.
  *
- * <p>In effect {@code TcpConnectionHandler} and {@code TcpConnection} are the
- * contracts any sub-class must adapt to while using {@link StompEncoder} and
- * {@link StompDecoder} to encode and decode STOMP messages.
+ * <p>In effect, {@code TcpConnectionHandler} and {@code TcpConnection} are the
+ * contracts that any subclass must adapt to while using {@link StompEncoder}
+ * and {@link StompDecoder} to encode and decode STOMP messages.
  *
  * @author Rossen Stoyanchev
  * @since 4.2
@@ -58,7 +57,7 @@ public abstract class StompClientSupport {
 	 * @param messageConverter the message converter to use
 	 */
 	public void setMessageConverter(MessageConverter messageConverter) {
-		Assert.notNull(messageConverter, "'messageConverter' must not be null");
+		Assert.notNull(messageConverter, "MessageConverter must not be null");
 		this.messageConverter = messageConverter;
 	}
 
@@ -92,7 +91,7 @@ public abstract class StompClientSupport {
 	 * CONNECT frame. The first number represents how often the client will write
 	 * or send a heart-beat. The second is how often the server should write.
 	 * A value of 0 means no heart-beats.
-	 * <p>By default this is set to "10000,10000" but sub-classes may override
+	 * <p>By default this is set to "10000,10000" but subclasses may override
 	 * that default and for example set it to "0,0" if they require a
 	 * TaskScheduler to be configured first.
 	 * @param heartbeat the value for the CONNECT "heart-beat" header
@@ -100,22 +99,23 @@ public abstract class StompClientSupport {
 	 * http://stomp.github.io/stomp-specification-1.2.html#Heart-beating</a>
 	 */
 	public void setDefaultHeartbeat(long[] heartbeat) {
-		Assert.notNull(heartbeat);
-		Assert.isTrue(heartbeat[0] >= 0 && heartbeat[1] >=0 , "Invalid heart-beat: "  + Arrays.toString(heartbeat));
+		if (heartbeat == null || heartbeat.length != 2 || heartbeat[0] < 0 || heartbeat[1] < 0) {
+			throw new IllegalArgumentException("Invalid heart-beat: " + Arrays.toString(heartbeat));
+		}
 		this.defaultHeartbeat = heartbeat;
 	}
 
 	/**
-	 * Return the configured default heart-beat value, never {@code null}.
+	 * Return the configured default heart-beat value (never {@code null}).
 	 */
 	public long[] getDefaultHeartbeat() {
 		return this.defaultHeartbeat;
 	}
 
 	/**
-	 * Whether heartbeats are enabled. Returns {@code false} if
-	 * {@link #setDefaultHeartbeat defaultHeartbeat} is set to "0,0", and
-	 * {@code true} otherwise.
+	 * Determine whether heartbeats are enabled.
+	 * <p>Returns {@code false} if {@link #setDefaultHeartbeat defaultHeartbeat}
+	 * is set to "0,0", and {@code true} otherwise.
 	 */
 	public boolean isDefaultHeartbeatEnabled() {
 		return (getDefaultHeartbeat() != null && getDefaultHeartbeat()[0] != 0 && getDefaultHeartbeat()[1] != 0);
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java
index 28a636a9..3bd92ebe 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -53,7 +53,6 @@ public class StompDecoder {
 
 	private static final Log logger = LogFactory.getLog(StompDecoder.class);
 
-
 	private MessageHeaderInitializer headerInitializer;
 
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java
index 228fbcdb..86d7a7bf 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -19,7 +19,7 @@ package org.springframework.messaging.simp.stomp;
 import java.io.ByteArrayOutputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
-import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,14 +39,15 @@ import org.springframework.util.Assert;
  * @author Andy Wilkinson
  * @author Rossen Stoyanchev
  * @since 4.0
+ * @see StompDecoder
  */
-public final class StompEncoder  {
+public class StompEncoder  {
 
 	private static final byte LF = '\n';
 
 	private static final byte COLON = ':';
 
-	private final Log logger = LogFactory.getLog(StompEncoder.class);
+	private static final Log logger = LogFactory.getLog(StompEncoder.class);
 
 
 	/**
@@ -78,9 +79,13 @@ public final class StompEncoder  {
 				}
 				output.write(StompDecoder.HEARTBEAT_PAYLOAD);
 			}
+
 			else {
 				StompCommand command = StompHeaderAccessor.getCommand(headers);
-				Assert.notNull(command, "Missing STOMP command: " + headers);
+				if (command == null) {
+					throw new IllegalStateException("Missing STOMP command: " + headers);
+				}
+
 				output.write(command.toString().getBytes(StompDecoder.UTF8_CHARSET));
 				output.write(LF);
 				writeHeaders(command, headers, payload, output);
@@ -96,8 +101,8 @@ public final class StompEncoder  {
 		}
 	}
 
-	private void writeHeaders(StompCommand command, Map<String, Object> headers, byte[] payload, DataOutputStream output)
-			throws IOException {
+	private void writeHeaders(StompCommand command, Map<String, Object> headers, byte[] payload,
+			DataOutputStream output) throws IOException {
 
 		@SuppressWarnings("unchecked")
 		Map<String,List<String>> nativeHeaders =
@@ -114,22 +119,25 @@ public final class StompEncoder  {
 		boolean shouldEscape = (command != StompCommand.CONNECT && command != StompCommand.CONNECTED);
 
 		for (Entry<String, List<String>> entry : nativeHeaders.entrySet()) {
-			byte[] key = encodeHeaderString(entry.getKey(), shouldEscape);
 			if (command.requiresContentLength() && "content-length".equals(entry.getKey())) {
 				continue;
 			}
+
 			List<String> values = entry.getValue();
 			if (StompCommand.CONNECT.equals(command) &&
 					StompHeaderAccessor.STOMP_PASSCODE_HEADER.equals(entry.getKey())) {
-				values = Arrays.asList(StompHeaderAccessor.getPasscode(headers));
+				values = Collections.singletonList(StompHeaderAccessor.getPasscode(headers));
 			}
+
+			byte[] encodedKey = encodeHeaderString(entry.getKey(), shouldEscape);
 			for (String value : values) {
-				output.write(key);
+				output.write(encodedKey);
 				output.write(COLON);
 				output.write(encodeHeaderString(value, shouldEscape));
 				output.write(LF);
 			}
 		}
+
 		if (command.requiresContentLength()) {
 			int contentLength = payload.length;
 			output.write("content-length:".getBytes(StompDecoder.UTF8_CHARSET));
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java
index dc467a9f..d38f8906 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java
@@ -29,21 +29,21 @@ import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
 import org.springframework.messaging.simp.SimpMessageType;
 import org.springframework.messaging.support.MessageHeaderAccessor;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.StringUtils;
 
 /**
- * A {@code MessageHeaderAccessor} to use when creating a {@code Message} from a
- * decoded STOMP frame, or when encoding a {@code Message} to a STOMP frame.
+ * A {@code MessageHeaderAccessor} to use when creating a {@code Message} from
+ * a decoded STOMP frame, or when encoding a {@code Message} to a STOMP frame.
  *
- * <p>When created from STOMP frame content, the actual STOMP headers are stored
- * in the native header sub-map managed by the parent class
+ * <p>When created from STOMP frame content, the actual STOMP headers are
+ * stored in the native header sub-map managed by the parent class
  * {@link org.springframework.messaging.support.NativeMessageHeaderAccessor}
- * while the parent class
- * {@link org.springframework.messaging.simp.SimpMessageHeaderAccessor} manages
- * common processing headers some of which are based on STOMP headers (e.g.
- * destination, content-type, etc).
+ * while the parent class {@link SimpMessageHeaderAccessor} manages common
+ * processing headers some of which are based on STOMP headers
+ * (e.g. destination, content-type, etc).
  *
  * <p>An instance of this class can also be created by wrapping an existing
  * {@code Message}. That message may have been created with the more generic
@@ -210,7 +210,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 		}
 		trySetStompHeaderForSubscriptionId();
 		if (getMessageId() == null) {
-			String messageId = getSessionId() + "-" + messageIdCounter.getAndIncrement();
+			String messageId = getSessionId() + '-' + messageIdCounter.getAndIncrement();
 			setNativeHeader(STOMP_MESSAGE_ID_HEADER, messageId);
 		}
 	}
@@ -502,12 +502,8 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 	}
 
 	public static Integer getContentLength(Map<String, List<String>> nativeHeaders) {
-		if (nativeHeaders.containsKey(STOMP_CONTENT_LENGTH_HEADER)) {
-			List<String> values = nativeHeaders.get(STOMP_CONTENT_LENGTH_HEADER);
-			String value = (values != null ? values.get(0) : null);
-			return Integer.valueOf(value);
-		}
-		return null;
+		List<String> values = nativeHeaders.get(STOMP_CONTENT_LENGTH_HEADER);
+		return (!CollectionUtils.isEmpty(values) ? Integer.valueOf(values.get(0)) : null);
 	}
 
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/simp/user/MultiServerUserRegistry.java b/spring-messaging/src/main/java/org/springframework/messaging/simp/user/MultiServerUserRegistry.java
index bdfb9112..7e24fafd 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/simp/user/MultiServerUserRegistry.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/simp/user/MultiServerUserRegistry.java
@@ -77,7 +77,7 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		catch (UnknownHostException ex) {
 			host = "unknown";
 		}
-		return host + "-" + UUID.randomUUID();
+		return host + '-' + UUID.randomUUID();
 	}
 
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/support/MessageHeaderAccessor.java b/spring-messaging/src/main/java/org/springframework/messaging/support/MessageHeaderAccessor.java
index cbd11bb4..967fd664 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/support/MessageHeaderAccessor.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/support/MessageHeaderAccessor.java
@@ -566,7 +566,7 @@ public class MessageHeaderAccessor {
 	 * of the given {@code Message}, or {@code null} if that's not available or if
 	 * its type does not match the required type.
 	 * <p>This is for cases where the existence of an accessor is strongly expected
-	 * (to be followed up with an assertion) or will created if not provided.
+	 * (followed up with an assertion) or where an accessor will be created otherwise.
 	 * @return an accessor instance of the specified type, or {@code null} if none
 	 * @since 4.1
 	 */