Replace use of PubSub header name literals

spring-websocket/src/main/java/org/springframework/web/messaging/service/method/MessageBodyArgumentResolver.java

@@ -21,6 +21,7 @@ import java.util.List;
 import org.springframework.core.MethodParameter;
 import org.springframework.http.MediaType;
 import org.springframework.messaging.Message;
+import org.springframework.web.messaging.PubSubHeaders;
 import org.springframework.web.messaging.annotation.MessageBody;
 import org.springframework.web.messaging.converter.CompositeMessageConverter;
 import org.springframework.web.messaging.converter.MessageConversionException;
@@ -51,7 +52,7 @@ public class MessageBodyArgumentResolver implements ArgumentResolver {
 		Object arg = null;
 
 		MessageBody annot = parameter.getParameterAnnotation(MessageBody.class);
-		MediaType contentType = (MediaType) message.getHeaders().get("content-type");
+		MediaType contentType = (MediaType) message.getHeaders().get(PubSubHeaders.CONTENT_TYPE);
 
 		if (annot == null || annot.required()) {
 			Class<?> sourceType = message.getPayload().getClass();

spring-websocket/src/main/java/org/springframework/web/messaging/stomp/support/StompRelayPubSubMessageHandler.java

@@ -38,6 +38,7 @@ import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.SubscribableChannel;
 import org.springframework.util.Assert;
 import org.springframework.web.messaging.MessageType;
+import org.springframework.web.messaging.PubSubHeaders;
 import org.springframework.web.messaging.converter.CompositeMessageConverter;
 import org.springframework.web.messaging.converter.MessageConverter;
 import org.springframework.web.messaging.service.AbstractPubSubMessageHandler;
@@ -85,7 +86,7 @@ public class StompRelayPubSubMessageHandler extends AbstractPubSubMessageHandler
 	@Override
 	public void handleConnect(Message<?> message) {
 
-		String sessionId = (String) message.getHeaders().get("sessionId");
+		String sessionId = (String) message.getHeaders().get(PubSubHeaders.SESSION_ID);
 
 		RelaySession session = new RelaySession();
 		this.relaySessions.put(sessionId, session);
@@ -168,7 +169,7 @@ public class StompRelayPubSubMessageHandler extends AbstractPubSubMessageHandler
 
 	@Override
 	public void handleOther(Message<?> message) {
-		StompCommand command = (StompCommand) message.getHeaders().get("stompCommand");
+		StompCommand command = (StompCommand) message.getHeaders().get(PubSubHeaders.PROTOCOL_MESSAGE_TYPE);
 		Assert.notNull(command, "Expected STOMP command: " + message.getHeaders());
 		forwardMessage(message, command);
 	}