This repository uses the BTW-gradle-example repository as the dev environment.
This addon for BTW introduces additional block metadata capabilities for addon developers by adding extra metadata to each block, 32 bits to be precise. These can be accessed using the new extra metadata methods, which work exactly like the standard ones, just with 32 bits.
Be aware of the usual Java implications when handling (un-)signed integers. Internally, the extra metadata integers are handled unsigned, so all 32 bits can actually be used.