Clarification needed : FetchForWriting usage with MultiStream projection

[Astenna]

According to docs and issue 3379 FetchForWriting API is only possible with single stream aggregation projections. Hence, I would expect some kind of exception / error on an attempt to use FetchForWriting<T> where T is an aggregate coming from an inline, multi-stream projection. However, it seems to work correctly without any problems.

Can someone clarify? It's probably either of these two:

• the FetchForWriting<T> can be used with multistream, inline projections (then docs need clarification/update)
• the FetchForWriting<T> can NOT be used with multistream (then why is no exception thrown?)

I'm using marten 7.29.0.