Port the build to Gradle

Closes gh-19609
Closes gh-19608

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/projects/start-stop/pom.xml

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>org.springframework.boot.maven.it</groupId>
+	<artifactId>start-stop-fork</artifactId>
+	<version>0.0.1.BUILD-SNAPSHOT</version>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<maven.compiler.source>@java.version@</maven.compiler.source>
+		<maven.compiler.target>@java.version@</maven.compiler.target>
+	</properties>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.codehaus.mojo</groupId>
+				<artifactId>build-helper-maven-plugin</artifactId>
+				<version>@build-helper-maven-plugin.version@</version>
+				<executions>
+					<execution>
+						<id>reserve-jmx-port</id>
+						<goals>
+							<goal>reserve-network-port</goal>
+						</goals>
+						<phase>process-resources</phase>
+						<configuration>
+							<portNames>
+								<portName>jmx.port</portName>
+							</portNames>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+			<plugin>
+				<groupId>@project.groupId@</groupId>
+				<artifactId>@project.artifactId@</artifactId>
+				<version>@project.version@</version>
+				<executions>
+					<execution>
+						<id>pre-integration-test</id>
+						<goals>
+							<goal>start</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>post-integration-test</id>
+						<goals>
+							<goal>stop</goal>
+						</goals>
+					</execution>
+				</executions>
+				<configuration>
+					<jmxPort>${jmx.port}</jmxPort>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+</project>

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/projects/start-stop/src/main/java/org/test/SampleApplication.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.test;
+
+import java.lang.management.ManagementFactory;
+
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+
+/**
+ * This sample app simulates the JMX Mbean that is exposed by the Spring Boot application.
+ */
+public class SampleApplication {
+
+	private static final Object lock = new Object();
+
+	public static void main(String[] args) throws Exception {
+		MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
+		ObjectName name = new ObjectName(
+				"org.springframework.boot:type=Admin,name=SpringApplication");
+		SpringApplicationAdmin mbean = new SpringApplicationAdmin();
+		mbs.registerMBean(mbean, name);
+
+		// Flag the app as ready
+		mbean.ready = true;
+
+		int waitAttempts = 0;
+		while (!mbean.shutdownInvoked) {
+			if (waitAttempts > 30) {
+				throw new IllegalStateException(
+						"Shutdown should have been invoked by now");
+			}
+			synchronized (lock) {
+				lock.wait(250);
+			}
+			waitAttempts++;
+		}
+	}
+
+	public interface SpringApplicationAdminMXBean {
+
+		boolean isReady();
+
+		void shutdown();
+
+	}
+
+	static class SpringApplicationAdmin implements SpringApplicationAdminMXBean {
+
+		private boolean ready;
+
+		private boolean shutdownInvoked;
+
+		@Override
+		public boolean isReady() {
+			System.out.println("isReady: " + this.ready);
+			return this.ready;
+		}
+
+		@Override
+		public void shutdown() {
+			this.shutdownInvoked = true;
+			System.out.println("Shutdown requested");
+		}
+
+	}
+
+}