Why flet_map doesn't accept custom children?

[Bbalduzz]

While working with flet_map I noticed a couple of things that could be improved.
The first one is the lack of headers support in the TileLayer (supported in the official flutter_map package), and the second one is the limitations for the layers children's:

https://github.com/flet-dev/flet-map/blob/dfa3cf6776b0dc5f238227d5f378cda7be190eaf/src/flutter/flet_map/lib/src/map.dart#L42

The first one is easily fixable and I've already created a pr for it (flet-dev/flet-map#4)
But its unclear to me why it has been decided to limit the type of the map's layers children.