Correct but I don't need it for metadata. I was just using the StateMapper to help create/organize my BlockStates and item folders with an inner hierarchy that would make it more manageable and more easily traceable for the blocks im working with.
i.e.
blockstates/someAbstractGroup (not metadata, just individual blocks) / someBlocksinhere.json'
blockStates/anotherGroup/[someotherblock.json, someotherblock.json], etc.
if that makes sense
heres how it used to be in 1.12 for reference: