This is only for FG_1.2(for minecraft 1.7.10). Minecraft mod development framework used by Forge and FML for the gradle build system
When class extends class from other jar that extends some minecraft class (Block, TileEntity...) and you references methods or fields that must be obfuscated from it you can ran into obfuscation problems, this already happened with me many times but fixed itself and i still don't know reason of this (removing temporary build files not fixes it)   
This issue appears to be discussing a feature request or bug report related to the repository. Based on the content, it seems to be still under discussion. The issue was opened by iocmet and has received 10 comments.