Make checkstyle task fail, when new warnings appear.

      <formatter type="plain"

                 toFile="${generated}/checkstyle_report.txt"/>

    </checkstyle>

    <exec executable="cat" outputproperty="checkstyle.result">

      <arg value="${generated}/checkstyle_report.txt" />

    </exec>

    <fail message="Checkstyle complaints: ${checkstyle.result}" >

      <condition>

        <not>

          <length string="${checkstyle.result}"

                  length="29" />

        </not>

      </condition>

    </fail>

  </target>

  <target name="war"