Warning: If you want to add your own Ant targets, you should add them to build.xml and not to maven-build.xml.
The build.xml file uses the import task of Ant. So, you can override the generated targets in the build.xml file. For instance:
<?xml version="1.0" encoding="UTF-8"?>
<!-- ====================================================================== -->
<!-- Ant build file (http://ant.apache.org/) for Ant 1.6.2 or above. -->
<!-- ====================================================================== -->
<project name="%PROJECT_ARTIFACT_ID%" default="package" basedir=".">
<!-- ====================================================================== -->
<!-- Import maven-build.xml into the current project -->
<!-- ====================================================================== -->
<import file="maven-build.xml"/>
<!-- ====================================================================== -->
<!-- Help target -->
<!-- ====================================================================== -->
<target name="help">
<echo message="Please run: $ant -projecthelp"/>
</target>
<!-- ====================================================================== -->
<!-- Override the jar target from maven-build.xml -->
<!-- ====================================================================== -->
<target name="jar">
<echo message="Nothing to do."/>
</target>
</project>