Support STOMP in addition to CONNECT frame

One is literally an alias for the other with "the advantage that a
protocol sniffer/discriminator will be able to differentiate the STOMP
connection from an HTTP connection".

Closes gh-22652

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandler.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -521,7 +521,7 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 			return;
 		}
 
-		if (StompCommand.CONNECT.equals(command)) {
+		if (StompCommand.CONNECT.equals(command) || StompCommand.STOMP.equals(command)) {
 			if (logger.isDebugEnabled()) {
 				logger.debug(stompAccessor.getShortLogMessage(EMPTY_PAYLOAD));
 			}

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -138,7 +138,8 @@ public class StompEncoder  {
 			return;
 		}
 
-		boolean shouldEscape = (command != StompCommand.CONNECT && command != StompCommand.CONNECTED);
+		boolean shouldEscape = (command != StompCommand.CONNECT && command != StompCommand.STOMP
+				&& command != StompCommand.CONNECTED);
 
 		for (Entry<String, List<String>> entry : nativeHeaders.entrySet()) {
 			if (command.requiresContentLength() && "content-length".equals(entry.getKey())) {
@@ -146,7 +147,7 @@ public class StompEncoder  {
 			}
 
 			List<String> values = entry.getValue();
-			if (StompCommand.CONNECT.equals(command) &&
+			if ((StompCommand.CONNECT.equals(command) || StompCommand.STOMP.equals(command)) &&
 					StompHeaderAccessor.STOMP_PASSCODE_HEADER.equals(entry.getKey())) {
 				values = Collections.singletonList(StompHeaderAccessor.getPasscode(headers));
 			}

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompHeaderAccessor.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -160,7 +160,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 				super.setSubscriptionId(value);
 			}
 		}
-		else if (StompCommand.CONNECT.equals(command)) {
+		else if (StompCommand.CONNECT.equals(command) || StompCommand.STOMP.equals(command)) {
 			protectPasscode();
 		}
 	}
@@ -425,6 +425,10 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 			Principal user = getUser();
 			return "CONNECT" + (user != null ? " user=" + user.getName() : "") + appendSession();
 		}
+		else if (StompCommand.STOMP.equals(command)) {
+			Principal user = getUser();
+			return "STOMP" + (user != null ? " user=" + user.getName() : "") + appendSession();
+		}
 		else if (StompCommand.CONNECTED.equals(command)) {
 			return "CONNECTED heart-beat=" + Arrays.toString(getHeartbeat()) + appendSession();
 		}

spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompHeaderAccessorTests.java

 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -102,9 +102,9 @@ public class StompHeaderAccessorTests {
 		extHeaders.add(StompHeaderAccessor.STOMP_LOGIN_HEADER, "joe");
 		extHeaders.add(StompHeaderAccessor.STOMP_PASSCODE_HEADER, "joe123");
 
-		StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.CONNECT, extHeaders);
+		StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.STOMP, extHeaders);
 
-		assertEquals(StompCommand.CONNECT, headerAccessor.getCommand());
+		assertEquals(StompCommand.STOMP, headerAccessor.getCommand());
 		assertEquals(SimpMessageType.CONNECT, headerAccessor.getMessageType());
 		assertNotNull(headerAccessor.getHeader("stompCredentials"));
 		assertEquals("joe", headerAccessor.getLogin());

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

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -271,7 +271,7 @@ public class StompSubProtocolHandler implements SubProtocolHandler, ApplicationE
 				}
 
 				StompCommand command = headerAccessor.getCommand();
-				boolean isConnect = StompCommand.CONNECT.equals(command);
+				boolean isConnect = StompCommand.CONNECT.equals(command) || StompCommand.STOMP.equals(command);
 				if (isConnect) {
 					this.stats.incrementConnectCount();
 				}

spring-websocket/src/test/java/org/springframework/web/socket/messaging/StompSubProtocolHandlerTests.java

 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -289,7 +289,7 @@ public class StompSubProtocolHandlerTests {
 	@Test
 	public void handleMessageFromClient() {
 
-		TextMessage textMessage = StompTextMessageBuilder.create(StompCommand.CONNECT).headers(
+		TextMessage textMessage = StompTextMessageBuilder.create(StompCommand.STOMP).headers(
 				"login:guest", "passcode:guest", "accept-version:1.1,1.0", "heart-beat:10000,10000").build();
 
 		this.protocolHandler.afterSessionStarted(this.session, this.channel);
@@ -307,7 +307,7 @@ public class StompSubProtocolHandlerTests {
 		assertArrayEquals(new long[] {10000, 10000}, SimpMessageHeaderAccessor.getHeartbeat(actual.getHeaders()));
 
 		StompHeaderAccessor stompAccessor = StompHeaderAccessor.wrap(actual);
-		assertEquals(StompCommand.CONNECT, stompAccessor.getCommand());
+		assertEquals(StompCommand.STOMP, stompAccessor.getCommand());
 		assertEquals("guest", stompAccessor.getLogin());
 		assertEquals("guest", stompAccessor.getPasscode());
 		assertArrayEquals(new long[] {10000, 10000}, stompAccessor.getHeartbeat());