String sessionId = "sess1";
String subscriptionId = "subs1";
String destination = "/dest";
Message<?> inputMessage = createInputMessage(sessionId, subscriptionId, destination, null);
MessageSendingOperations messagingTemplate = Mockito.mock(MessageSendingOperations.class);
SubscriptionMethodReturnValueHandler handler = new SubscriptionMethodReturnValueHandler(messagingTemplate);
handler.handleReturnValue(PAYLOAD, this.subscribeEventReturnType, inputMessage);
ArgumentCaptor<MessageHeaders> captor = ArgumentCaptor.forClass(MessageHeaders.class);