Fixes https://github.com/spring-projects/spring-integration/issues/8785 The `ClientWebSocketContainer.start()` delegates to the `IntegrationWebSocketConnectionManager` which performs an async connection to the server. * Wait for `connectionLatch` in the `ClientWebSocketContainer.start()` and check for `this.openConnectionException != null` to re-throw. Mark `ClientWebSocketContainer` as stopped in that case **Cherry-pick to `6.1.x` & `6.0.x`**