Use custom port for RSocket server over websocket

Prior to this change, the custom port configured for the RSocket
server would not be used if the server factory is using the
websocket transport and is provided with a custom
`ReactorResourceFactory`.

Fixes gh-18200

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/rsocket/netty/NettyRSocketServerFactory.java

@@ -128,8 +128,8 @@ public class NettyRSocketServerFactory implements RSocketServerFactory, Configur
 	private ServerTransport<CloseableChannel> createTransport() {
 		if (this.transport == RSocketServer.TRANSPORT.WEBSOCKET) {
 			if (this.resourceFactory != null) {
-				HttpServer httpServer = HttpServer.create()
-						.tcpConfiguration((tcpServer) -> tcpServer.runOn(this.resourceFactory.getLoopResources()));
+				HttpServer httpServer = HttpServer.create().tcpConfiguration((tcpServer) -> tcpServer
+						.runOn(this.resourceFactory.getLoopResources()).addressSupplier(this::getListenAddress));
 				return WebsocketServerTransport.create(httpServer);
 			}
 			else {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/rsocket/netty/NettyRSocketServerFactoryTests.java

@@ -40,6 +40,7 @@ import org.springframework.boot.rsocket.server.ServerRSocketFactoryCustomizer;
 import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.codec.StringDecoder;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
+import org.springframework.http.client.reactive.ReactorResourceFactory;
 import org.springframework.messaging.rsocket.RSocketRequester;
 import org.springframework.messaging.rsocket.RSocketStrategies;
 import org.springframework.util.SocketUtils;
@@ -54,6 +55,7 @@ import static org.mockito.Mockito.mock;
  * Tests for {@link NettyRSocketServerFactory}
  *
  * @author Brian Clozel
+ * @author Leo Li
  */
 class NettyRSocketServerFactoryTests {
 
@@ -93,6 +95,7 @@ class NettyRSocketServerFactoryTests {
 		String payload = "test payload";
 		String response = this.requester.route("test").data(payload).retrieveMono(String.class).block(TIMEOUT);
 
+		assertThat(this.rSocketServer.address().getPort()).isEqualTo(specificPort);
 		assertThat(response).isEqualTo(payload);
 		assertThat(this.rSocketServer.address().getPort()).isEqualTo(specificPort);
 	}
@@ -106,9 +109,29 @@ class NettyRSocketServerFactoryTests {
 		this.requester = createRSocketWebSocketClient();
 		String payload = "test payload";
 		String response = this.requester.route("test").data(payload).retrieveMono(String.class).block(TIMEOUT);
+
 		assertThat(response).isEqualTo(payload);
 	}
 
+	@Test
+	void websocketTransportWithReactorResource() {
+		NettyRSocketServerFactory factory = getFactory();
+		factory.setTransport(RSocketServer.TRANSPORT.WEBSOCKET);
+		ReactorResourceFactory resourceFactory = new ReactorResourceFactory();
+		resourceFactory.afterPropertiesSet();
+		factory.setResourceFactory(resourceFactory);
+		int specificPort = SocketUtils.findAvailableTcpPort(41000);
+		factory.setPort(specificPort);
+		this.rSocketServer = factory.create(new EchoRequestResponseAcceptor());
+		this.rSocketServer.start();
+		this.requester = createRSocketWebSocketClient();
+		String payload = "test payload";
+		String response = this.requester.route("test").data(payload).retrieveMono(String.class).block(TIMEOUT);
+
+		assertThat(response).isEqualTo(payload);
+		assertThat(this.rSocketServer.address().getPort()).isEqualTo(specificPort);
+	}
+
 	@Test
 	void serverCustomizers() {
 		NettyRSocketServerFactory factory = getFactory();