Java 5 compatible classes with jwsc/jws task

Question

We are compiling all our jars with target="5" so that the class files remain compatible with the older servers still running JDK5. Unfortunately, the web service compiled by jwsc takes the default java version, in this case 6.

    <jwsc   srcdir="${src.dir}" destdir="${dist.dir}" classpathref="project.class.path" debug="true">
        <jws file="org/foo/MainWebServiceImpl.java"
            compiledWsdl="../FooClient/gen-compiled-wsdl/${wsdl.foo.filebasename}_wsdl.jar" />
    </jwsc>

I don't have a "target" attribute in jwsc nor jws and the sub-elements don't seem to help. How can I get this task to compile Java 5 compatible classes ?

I am currently letting the jenkins server compile the code but I hate having to commit untested code to be able to deploy and test it.