Use ProcessHandler to get the process ID

Closes gh-28178

Author: wilkinsona

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/system/ApplicationPid.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -20,7 +20,6 @@
 import java.io.FileNotFoundException;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.lang.management.ManagementFactory;
 import java.nio.file.Files;
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.Set;
@@ -51,8 +50,7 @@ protected ApplicationPid(String pid) {
 
 	private String getPid() {
 		try {
-			String jvmName = ManagementFactory.getRuntimeMXBean().getName();
-			return jvmName.split("@")[0];
+			return Long.toString(ProcessHandle.current().pid());
 		}
 		catch (Throwable ex) {
 			return null;