This patch hangs the server.

Apply the patch, load the UI, then run ./bin/devcam put -filenodes -permanode doc.
Server reliably hangs for me.

Change-Id: I4057d4575515d1298ab83e58059b669a6f2bdacb
search: WIP notes on RelationConstraint. Not implemented yet.

Change-Id: Ic179a046da146706b57d7e6e031e1665deedd036