OCL25 — Collection{} is Collection(OclVoid){}

Issue 12953 considered the problem of the element type of an empty collection and rejected OclVoid (Option 1) because Set{}->including(1) would fail.

This rejection is appropriate when the collection is modified as in Java, but is inappropriate for OCL where a new Collection is created. There is therefore no problem in deciding that the most derived common element type of Set{} (OclVoid) and 1 (Integer) is Integer causing Set(Integer)::including(Integer) to be invoked.