jBPM5 and Drools share the same API. This is why the javadoc only shows org.drools.xxx packages. If you are going to be a user of those APIs, then the classes shown in the javadoc should be enough.
If you want to go deeper, then I would suggest you to download the source code of jbpm and create the specific javadocs.
The main classes you need to understand if you want to interact with your processes are:
- KnowledgeBuilder
- KnowledgeBase
- StatefulKnowledgeSession
I would suggst you to read jBPMs documentation (the user manual) first in order to understand how can you compile, start and interact with your processes.
Best Regards,