Ok I think I've found:
the IOUtils.class is duplicated inside
./jbpm-gwt-console-server/WEB-INF/lib/org.apache.batik.pdf_1.6.0.v201105071520.jar
which comes from birt-runtime...zip added during the ant install.jBPM-gwt-console.into.jboss7 -> install.reporting.into.jboss7
I removed the jar and now it's ok...
well maybe I removed some pdf functionallity, but for now it's ok
vittorio