ant/src/etc/testcases/taskdefs/dynamictask.xml

<?xml version="1.0"?>

<project name="dynamic-test" default="simple">

  <path id="testclasses">
    <pathelement location="../../../../build/testcases" />
    <pathelement path="${java.class.path}" />
  </path>

  <target name="simple">
    <taskdef name="dyna"
             classname="org.apache.tools.ant.taskdefs.DynamicTask">
      <classpath refid="testclasses" />
    </taskdef>
    <dyna prop1="1" prop2="2">
      <sub prop3="3"/>
      <anything prop4="4"/>
    </dyna>
  </target>

</project>