Ensure web containers are stopped after close

Update `EmbeddedServletContainer` implementations to ensure that stop
can be called even if start has not. This allows servers that are
partially started during `initialize()` to still be shut down.

This commit fixes a regression caused by commit 0af53b361f.

See gh-8036
Fixes gh-8224
Closes gh-8227

spring-boot/src/main/java/org/springframework/boot/context/embedded/jetty/JettyEmbeddedServletContainer.java

@@ -205,9 +205,6 @@ public class JettyEmbeddedServletContainer implements EmbeddedServletContainer {
 	@Override
 	public void stop() {
 		synchronized (this.monitor) {
-			if (!this.started) {
-				return;
-			}
 			this.started = false;
 			try {
 				this.server.stop();

spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainer.java

@@ -279,9 +279,6 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 	@Override
 	public void stop() throws EmbeddedServletContainerException {
 		synchronized (this.monitor) {
-			if (!this.started) {
-				return;
-			}
 			try {
 				this.started = false;
 				try {

spring-boot/src/test/java/org/springframework/boot/context/embedded/jetty/JettyEmbeddedServletContainerFactoryTests.java

@@ -143,6 +143,16 @@ public class JettyEmbeddedServletContainerFactoryTests
 				.isEmpty();
 	}
 
+	@Test
+	public void stopNoStart() throws Exception {
+		JettyEmbeddedServletContainerFactory factory = getFactory();
+		this.container = factory
+				.getEmbeddedServletContainer(exampleServletRegistration());
+		this.container.stop();
+		Server server = ((JettyEmbeddedServletContainer) this.container).getServer();
+		assertThat(server.isStopped()).isTrue();
+	}
+
 	@Override
 	protected void addConnector(final int port,
 			AbstractEmbeddedServletContainerFactory factory) {

spring-boot/src/test/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactoryTests.java

@@ -352,6 +352,16 @@ public class TomcatEmbeddedServletContainerFactoryTests
 				.doesNotContain("appears to have started a thread named [main]");
 	}
 
+	@Test
+	public void stopNoStart() throws Exception {
+		TomcatEmbeddedServletContainerFactory factory = getFactory();
+		this.container = factory
+				.getEmbeddedServletContainer(exampleServletRegistration());
+		this.container.stop();
+		Tomcat tomcat = ((TomcatEmbeddedServletContainer) this.container).getTomcat();
+		assertThat(tomcat.getServer().getState()).isSameAs(LifecycleState.DESTROYED);
+	}
+
 	@Override
 	protected void addConnector(int port,
 			AbstractEmbeddedServletContainerFactory factory) {