Add workingDirectory option for Maven plugin run/start

Add configuration option that specifies the working directory to use to
run/start the application via the Maven plugin.

Closes gh-6243

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/RunProcess.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.loader.tools;
 
 import java.io.BufferedReader;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.lang.reflect.Method;
@@ -41,16 +42,34 @@ public class RunProcess {
 
 	private static final long JUST_ENDED_LIMIT = 500;
 
+	private File workingDirectory;
+
 	private final String[] command;
 
 	private volatile Process process;
 
 	private volatile long endTime;
 
-	public RunProcess(String... command) {
+	/**
+	 * Creates new {@link RunProcess} instance for the specified command
+	 * and working directory.
+	 * @param workingDirectory the working directory of the child process or {@code null}
+	 * to run in the working directory of the current Java process
+	 * @param command the program to execute and it's arguments
+	 */
+	public RunProcess(File workingDirectory, String... command) {
+		this.workingDirectory = workingDirectory;
 		this.command = command;
 	}
 
+	/**
+	 * Creates new {@link RunProcess} instance for the specified command.
+	 * @param command the program to execute and it's arguments
+	 */
+	public RunProcess(String... command) {
+		this(null, command);
+	}
+
 	public int run(boolean waitForProcess, String... args) throws IOException {
 		return run(waitForProcess, Arrays.asList(args));
 	}
@@ -58,6 +77,7 @@ public class RunProcess {
 	protected int run(boolean waitForProcess, Collection<String> args)
 			throws IOException {
 		ProcessBuilder builder = new ProcessBuilder(this.command);
+		builder.directory(workingDirectory);
 		builder.command().addAll(args);
 		builder.redirectErrorStream(true);
 		boolean inheritedIO = inheritIO(builder);