I have process that invoke sub process using process state. I test the process with JUnit. When start test it says - ERROR (GraphElement.java:295) - action threw exception: can't create a process instance when processDefinition is null. This is because can't find the sub process definiton. How can I bound sub process definition to parent process definition. This is my code in JUnit test

ProcessDefinition definition = ProcessDefinition
 .parseXmlInputStream(new FileInputStream("jpdl\\parent\\processdefinition.xml"));
 ProcessDefinition definitionSub = ProcessDefinition
 .parseXmlInputStream(new FileInputStream("jpdl\\sub\\processdefinition.xml"));
 ProcessState st = (ProcessState)definition.getNode("Sub process Invoke");
 st.setProcessDefinition(definitionSub);
 ProcessInstance instance = new ProcessInstance(definition);
 instance.signal();