Summary:
Original commit changeset: 420d29d262b6
Reverts https://github.com/facebook/react-native/pull/25793 / D16515465
Union type property is not supported by codegen. We don't want to support unions yet and because the improvement is not that big and not yet published as stable for OSS (neither used anywhere internally) we can safely revert it.
Reviewed By: RSNara
Differential Revision: D16621228
fbshipit-source-id: 2fa416eef1ae353990860026ca97d2b0b429a852