Description of problem:
Bpm5Processor (or rather AbstractBpm5Action) adds the configured process definitions to the knowledgebase:

kbuilder.add(ResourceFactory.newClassPathResource(processDefName), ResourceType.BPMN2);

But there is no support for processes which are calling sub-processes. The class should be extended to read a list of process definition names from the configuration, and add them all to the kbase, so that process->sub-process invocation is possible from Bpm5Processor.