INT-4028: Fix ClientWebSocketContainer start/stop

JIRA: https://jira.spring.io/browse/INT-4028

Previously the `ClientWebSocketContainer` after the connection failure couldn't be restored even after `stop()/start()`
because the `openConnectionException` property hasn't been clear on `stop()`

* Add `openConnectionException = null` to `stopInternal()` logic
* Also clear `openConnectionException` and `clientSession` on `start()`
* Plus add recovery (restart) logic into the `getSession()` if the `!clientSession.isOpen()`

**Cherry-pick to 4.2.x**

Fix race condition around `start/stop`

The new `start/stop` logic brakes the in-flight connection.

* Introduce one more `connecting` flag to indicate that we are in connecting process.
* Absorb the a new test for `ClientWebSocketContainer` with the existing one. Looks like there is some extra session close in between.
* Adjust timeouts in the `StompIntegrationTests` to 20 secs. Add `org.apache.catalina` category for tracing logs

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

@@ -54,7 +54,7 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 
 	private final WebSocketHttpHeaders headers = new WebSocketHttpHeaders();
 
-	private final ConnectionManagerSupport connectionManager;
+	private final IntegrationWebSocketConnectionManager connectionManager;
 
 	private volatile CountDownLatch connectionLatch;
 
@@ -64,6 +64,8 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 
 	private volatile int connectionTimeout = DEFAULT_CONNECTION_TIMEOUT;
 
+	private volatile boolean connecting;
+
 	public ClientWebSocketContainer(WebSocketClient client, String uriTemplate, Object... uriVariables) {
 		Assert.notNull(client, "'client' must not be null");
 		this.connectionManager = new IntegrationWebSocketConnectionManager(client, uriTemplate, uriVariables);
@@ -108,18 +110,31 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 	@Override
 	public WebSocketSession getSession(String sessionId) {
 		if (isRunning()) {
+			if (!isConnected() && !this.connecting) {
+				stop();
+				start();
+			}
+
 			try {
 				this.connectionLatch.await(this.connectionTimeout, TimeUnit.SECONDS);
 			}
 			catch (InterruptedException e) {
 				logger.error("'clientSession' has not been established during 'openConnection'");
 			}
+			this.connecting = false;
 		}
-		if (this.openConnectionException != null) {
-			throw new IllegalStateException(this.openConnectionException);
+
+		try {
+			if (this.openConnectionException != null) {
+				throw new IllegalStateException(this.openConnectionException);
+			}
+			Assert.state(this.clientSession != null,
+					"'clientSession' has not been established. Consider to 'start' this container.");
+		}
+		catch (IllegalStateException e) {
+			stop();
+			throw e;
 		}
-		Assert.state(this.clientSession != null,
-				"'clientSession' has not been established. Consider to 'start' this container.");
 		return this.clientSession;
 	}
 
@@ -131,6 +146,15 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 		this.connectionManager.setPhase(phase);
 	}
 
+	/**
+	 * Return {@code true} if the {@link #clientSession} is opened.
+	 * @return the {@link WebSocketSession#isOpen()} state.
+	 * @since 4.2.6
+	 */
+	public boolean isConnected() {
+		return this.connectionManager.isConnected();
+	}
+
 	@Override
 	public boolean isAutoStartup() {
 		return this.connectionManager.isAutoStartup();
@@ -149,6 +173,8 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 	@Override
 	public synchronized void start() {
 		if (!isRunning()) {
+			this.clientSession = null;
+			this.openConnectionException = null;
 			this.connectionLatch = new CountDownLatch(1);
 			this.connectionManager.start();
 		}
@@ -178,7 +204,8 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 
 		private final boolean syncClientLifecycle;
 
-		private IntegrationWebSocketConnectionManager(WebSocketClient client, String uriTemplate, Object... uriVariables) {
+		private IntegrationWebSocketConnectionManager(WebSocketClient client, String uriTemplate,
+				Object... uriVariables) {
 			super(uriTemplate, uriVariables);
 			this.client = client;
 			this.syncClientLifecycle = ((client instanceof Lifecycle) && !((Lifecycle) client).isRunning());
@@ -189,6 +216,7 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 			if (this.syncClientLifecycle) {
 				((Lifecycle) this.client).start();
 			}
+			ClientWebSocketContainer.this.connecting = true;
 			super.startInternal();
 		}
 
@@ -202,14 +230,14 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 			}
 			finally {
 				ClientWebSocketContainer.this.clientSession = null;
+				ClientWebSocketContainer.this.openConnectionException = null;
 			}
 		}
 
 		@Override
 		protected void openConnection() {
-
 			logger.info("Connecting to WebSocket at " + getUri());
-			ClientWebSocketContainer.this.headers.setSecWebSocketProtocol(ClientWebSocketContainer.this.getSubProtocols());
+			ClientWebSocketContainer.this.headers.setSecWebSocketProtocol(getSubProtocols());
 			ListenableFuture<WebSocketSession> future =
 					this.client.doHandshake(ClientWebSocketContainer.this.webSocketHandler,
 							ClientWebSocketContainer.this.headers, getUri());
@@ -229,6 +257,7 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 					ClientWebSocketContainer.this.openConnectionException = t;
 					ClientWebSocketContainer.this.connectionLatch.countDown();
 				}
+
 			});
 		}