I remember that there was an issue with parameter ordering when using the Axis2 generated WSDL. Could you try if building a request against the original WSDL located at http://localhost:8080/ode/deployment/services/ProcessManagement
works?
EDIT: Now that I got the question correctly, the problem is that ODE expects the QName to be serialized differently, i.e. in the XML way instead of the Java way. Thus, instead of <ns:pid>{ode/bpel/unit-test}HelloWorld2-1</ns:pid>
the correct notation is <ns:pid xmlns:odetest="ode/bpel/unit-test">odetest:HelloWorld2-1</ns:pid>
.