Do you need to have something like a registry that does not need to be as complex as vanilla ones? (No network synchronization, no registry keys, just identifiers and objects).

Well, then the LiteRegistry class might interest you. Lite Registries are very simple objects: they are working through an identifier map, but you can use them for standard use of registries.

To create a LiteRegistry: use LiteRegistry#create.

And that's all.

DANGER

You can't register two entries with same identifiers, nor you can register the same entry twice in a Lite Registry.

You can now make use of LiteRegistry#register and registry information methods to match your needs.