custom_rules.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="Briar" default="help">
<target name="-pre-compile">
    <path id="project.all.jars.path">
        <path path="${toString:project.all.jars.path}"/>
        <fileset dir="${jar.libs.dir}">
            <include name="*.jar"/>
        </fileset>
        <fileset dir="${external.libs.dir}">
            <include name="*.jar"/>
        </fileset>
    </path>
</target>
</project>