Header does not provide information on what is expected from the object produced by GDExtension to be a valid Godot object

It's unclear what this `create` function should return:
https://github.com/godotengine/godot-headers/blob/e00386d464f87e39d8cc15fecde34802bb0f0200/godot/gdnative_interface.h#L228

But looking at the code in main godot repo, which handles this objects, it's obvious that there are specific requirement, including functions this object should have. `Godot-cpp` is complient with it as it appears.
Thus, to me it seems like it's important to cover this information in the header file. Be it a comment or (preferably) a struct.