build-javadoc.xml

<project>
  <property name="javadoc.dir" value="${basedir}/docs/javadoc"/>

  <target name="_generate-javadoc-fileset">
    <script language="javascript">
      <![CDATA[
        load("nashorn:mozilla_compat.js");
        importClass(org.apache.tools.ant.types.Path);
        importClass(org.apache.tools.ant.types.FileSet);
        importClass(java.lang.System);
        importClass(java.io.File);
        var modules = project.getProperty("modules").split(",");
        var fileset = new FileSet();
        fileset.setDir(new File(project.getProperty("modules.dir")));
        for (var i = 0; i < modules.length; ++i) {
          fileset.setIncludes(modules[i] + "/src/**/*.java");
        }
        project.setProjectReference(fileset);
        project.addReference("javadoc.files", fileset);
      ]]>
    </script>
  </target>

  <target name="javadoc" depends="_generate-javadoc-fileset" description="Generate Javadoc for all modules">
    <javadoc destdir="${javadoc.dir}">
      <fileset refid="javadoc.files"/>
      <classpath refid="path.common"/>
    </javadoc>
  </target>
</project>