I've looked at the spec but did not understand what should be happening with "An indirect reference to an annotation dictionary" and as a result I did not understand what "An array of such dictionaries" would look like. My guess is that it would be similar to the Annotation Ref in a Movie.

But as I could not come up with a test for this using Adobe DC and did not have at an example I did not add API for this and only added API for what I fully understood and could test.

My reasoning is that it is better not to have API, so that it can later be added, instead of wrong API that has to be carried around for compatibility.