See
http://www.lua.org/manual/5.2/manual.html#2.2As we discussed, I will remove the global environment and make one environment per file. I will remove the _G variable. _ENV will be the first upvalue in each chunk. If a chunk calls a Java function, that function will have access to the _ENV of the calling chunk and will modify that instead of the old global environment.
If you still agree, assign this back to me to do.