I can't find any clear documentation for you. But I can assure you that both ScreenOS and Junos can run OSPF directly on the vpn tunnel interfaces and pass the OSPF multicast making full neighbors. This feature was in ScreenOS for many years and was used to create automatic hub and spoke mulitpoint tunnels where you would not need to create any of the necessary routes for the sites to interconnect.
The feature was also then implemented in the SRX Junos code and works there as well.
I created the recipe because I encountered a some nuances getting this to work between ScreenOS and Junos so wanted to document and share the working example.