The version for Minecraft 1.12.2 DOES NOT WORK, it says it requires 1.12 or 1.12.1 or 1.12.2

changing build.properties accepted_mc_version=[1.12.2]
fixes issue

"mod_name=MapWriter
mod_group=vectron
mc_version=1.12.2
forge_version=14.23.0.2491
mcp_version=snapshot_20170207
mod_version=2.8.0
curse_project_id=231387
release_type=release
accepted_mc_version=[1.12.2]"

Changing mapping to 20170919 and fixing names will work as well

10 classes changed from 1.12.1 to 1.12.2 , so those names have to be fixed