Set virtualHost on StompBrokerRelayRegistration

Prior to this commit, one couldn't set the virtualHost property on
StompBrokerRelayMessageHandler via JavaConfig, since
StompBrokerRelayRegistration's API didn't offer that possibility.

This commit adds a new method in StompBrokerRelayRegistration's fluent
API to set the virtualHost used by StompBrokerRelayMessageHandler.
Note: this property is already configurable via xml config.

Issue: SPR-11433

spring-messaging/src/main/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistration.java

@@ -45,6 +45,8 @@ public class StompBrokerRelayRegistration extends AbstractBrokerRegistration {
 
 	private Long systemHeartbeatReceiveInterval;
 
+	private String virtualHost;
+
 	private boolean autoStartup = true;
 
 
@@ -146,6 +148,19 @@ public class StompBrokerRelayRegistration extends AbstractBrokerRegistration {
 		return this;
 	}
 
+	/**
+	 * Set the value of the "host" header to use in STOMP CONNECT frames. When this
+	 * property is configured, a "host" header will be added to every STOMP frame sent to
+	 * the STOMP broker. This may be useful for example in a cloud environment where the
+	 * actual host to which the TCP connection is established is different from the host
+	 * providing the cloud-based STOMP service.
+	 * <p>By default this property is not set.
+	 */
+	public StompBrokerRelayRegistration setVirtualHost(String virtualHost) {
+		this.virtualHost = virtualHost;
+		return this;
+	}
+
 	/**
 	 * Configure whether the {@link StompBrokerRelayMessageHandler} should start
 	 * automatically when the Spring ApplicationContext is refreshed.
@@ -177,6 +192,9 @@ public class StompBrokerRelayRegistration extends AbstractBrokerRegistration {
 		if (this.systemHeartbeatReceiveInterval != null) {
 			handler.setSystemHeartbeatReceiveInterval(this.systemHeartbeatReceiveInterval);
 		}
+		if(this.virtualHost != null) {
+			handler.setVirtualHost(this.virtualHost);
+		}
 
 		handler.setAutoStartup(this.autoStartup);
 

spring-messaging/src/test/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistrationTests.java

@@ -53,6 +53,7 @@ public class StompBrokerRelayRegistrationTests {
 		registration.setSystemPasscode("syspasscode");
 		registration.setSystemHeartbeatReceiveInterval(123);
 		registration.setSystemHeartbeatSendInterval(456);
+		registration.setVirtualHost("example.org");
 
 		StompBrokerRelayMessageHandler relayMessageHandler = registration.getMessageHandler(brokerChannel);
 
@@ -63,6 +64,7 @@ public class StompBrokerRelayRegistrationTests {
 		assertEquals("syspasscode", relayMessageHandler.getSystemPasscode());
 		assertEquals(123, relayMessageHandler.getSystemHeartbeatReceiveInterval());
 		assertEquals(456, relayMessageHandler.getSystemHeartbeatSendInterval());
+		assertEquals("example.org", relayMessageHandler.getVirtualHost());
 	}
 
 }