Adding an export definition to DummyCollection works, but a better solution may be desired.
Steps to Reproduce
Have a secondary module that calls OnCompositionChanged with a single entity handle. Linker error due to not exported DummyCollection.
That is good to know! I know Mieszko has been busy with several items around MassObservers. Can you elaborate on why you are calling OnCompositionChanged from another module? It could help us decide how we want to address this with either exporting the member or how best to have an outside function to call for keeping it from being exported.
-James