The testsuite/build.xml has out of date webservice.classpath that result in no valid webservice.classpath when using jdk5:

[starksm@banshee9100 testsuite]$ ant -projecthelp
Buildfile: build.xml
Overriding previous definition of reference to xdoclet.task.classpath
C:\cvs\JBoss4.0\jboss-4.0.x\testsuite\build.xml:285: Reference ${webservice.classpath} not found.

The webservice/output directory used as the basis for the avaialble check does not even exist when building with jdk5.