Add jvmArguments property to maven plugin

The maven plugin now forks a new process when it starts a boot app. This
makes remote debugging of the app impossible without the ability to pass
extra JVM arguments.

This commit adds a "jvmArguments" attribute to the RunMojo that defines
additional JVM arguments to set on the forked process.

Fixes gh-848

spring-boot-tools/spring-boot-maven-plugin/src/site/apt/examples/run-debug.apt.vm

@@ -0,0 +1,54 @@
+ -----
+ Debug the application
+ -----
+ Stephane Nicoll
+ -----
+ 2014-05-14
+ -----
+
+  The <<<run>>> goal forks a process for the boot application. It is possible to specify jvm arguments
+  to that forked process. The following configuration suspend the process until a debugger has joined
+  on port 5005
+
+---
+<project>
+  ...
+  <build>
+    ...
+    <plugins>
+      ...
+      <plugin>
+        <groupId>${project.groupId}</groupId>
+        <artifactId>${project.artifactId}</artifactId>
+        <version>${project.version}</version>
+        <executions>
+          <execution>
+            <goals>
+              <goal>run</goal>
+            </goals>
+            <configuration>
+              <jvmArguments>
+                  -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005
+              </jvmArguments>
+            </configuration>
+          </execution>
+        </executions>
+        ...
+      </plugin>
+      ...
+    </plugins>
+    ...
+  </build>
+  ...
+</project>
+---
+
+  These arguments can be specified on the command line as well, make sure to wrap that properly,
+  that is:
+
+---
+mvn spring-boot:run -Drun.jvmArguments="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005"
+---
+
+
+

spring-boot-tools/spring-boot-maven-plugin/src/site/apt/index.apt

@@ -40,6 +40,8 @@ Spring Boot Maven Plugin
 
   * {{{./examples/exclude-dependency.html}Exclude a dependency}}
 
+  * {{{./examples/run-debug.html}Debug the application}}
+
   []
 
 

spring-boot-tools/spring-boot-maven-plugin/src/site/apt/usage.apt.vm

@@ -99,6 +99,10 @@ Usage
 mvn spring-boot:run
 ---
 
+  The application is forked in a separate process. If you need to specify some JVM arguments
+  (i.e. for debugging purposes), you can use the <<<jvmArguments>>> parameter, see
+  {{{./examples/run-debug.html}Debug the application}} for more details.
+
   By default, any <<src/main/resources>> folder will be added to the application classpath
   when you run the application. This allows hot refreshing of resources which can be very
   useful when developing web applications. For example, you can work on HTML, CSS or JavaScipt

spring-boot-tools/spring-boot-maven-plugin/src/site/site.xml

@@ -9,6 +9,7 @@
 		<menu name="Examples">
 			<item name="Custom repackage classifier" href="examples/repackage-classifier.html"/>
 			<item name="Exclude a dependency" href="examples/exclude-dependency.html"/>
+			<item name="Debug the application" href="examples/run-debug.html"/>
 		</menu>
 		<menu ref="reports"/>
 	</body>