Within the properties for an AdHoc SubProcess node is a field to enter a completion condition for the node with a language selector for either java or mvel.
These completion conditions do not seem to be implemented. The only condition supported is
"getActivityInstanceAttribute("numberOfActiveInstances") == 0"
and the implementation of the condition in AdHocSubProcessHandler.java is a string compare against this expression and setting a flag "autoComplete" on the node.
This should be implemented to support any valid java or mvel expression given in the properties.