Separating stop and destroy in UndertowWebServer

gradle.properties

@@ -1,4 +1,4 @@
-version=3.5.5-SNAPSHOT
+version=3.5.5
 latestVersion=false
 spring.build-type=oss
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowWebServer.java

@@ -278,13 +278,30 @@ public void stop() throws WebServerException {
 				notifyGracefulCallback(false);
 			}
 			try {
-				this.undertow.stop();
+				if (this.undertow != null) {
+					this.undertow.stop();
+				}
+			}
+			catch (Exception ex) {
+				throw new WebServerException("Unable to stop embedded Undertow", ex);
+			}
+		}
+	}
+
+	@Override
+	public void destroy() {
+		synchronized (this.monitor) {
+			try {
+				if (this.started && this.undertow != null) {
+					this.started = false;
+					this.undertow.stop();
+				}
 				for (Closeable closeable : this.closeables) {
 					closeable.close();
 				}
 			}
 			catch (Exception ex) {
-				throw new WebServerException("Unable to stop Undertow", ex);
+				throw new WebServerException("Unable to stop embedded Undertow", ex);
 			}
 		}
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactoryTests.java

@@ -255,18 +255,6 @@ protected void portClashOfSecondaryConnectorResultsInPortInUseException() throws
 		super.portClashOfSecondaryConnectorResultsInPortInUseException();
 	}
 
-	@Test
-	@Override
-	@Disabled("Restart after stop is not supported with Undertow")
-	protected void restartAfterStop() {
-	}
-
-	@Test
-	@Override
-	@Disabled("Undertow's architecture prevents separating stop and destroy")
-	protected void servletContextListenerContextDestroyedIsNotCalledWhenContainerIsStopped() {
-	}
-
 	private void testAccessLog(String prefix, String suffix, String expectedFile)
 			throws IOException, URISyntaxException {
 		UndertowServletWebServerFactory factory = getFactory();