There is a collection of documents and diagrams in the jbpm-3.2-soa branch posing as bad excuses for design documentation.
http://anonsvn.jboss.org/repos/jbpm/jbpm3/branches/jbpm-3.2-soa/docs/

Checking the artifacts into the version control system as binaries ensures a limited audience for the content and, thanks to access control, an even smaller number of reviewers.

Additionally, these binary blobs take valuable space and time away from the continuous integration system.

All in all, the design documentation would fare much better in the knowledge base.