Sorry, my bad. I didn't describe my particular issue in detail.
My particular issue was that gtags didn't respect `--langdef=kotlin` config from
On second thought, it doesn't require changing exuberant-ctags.c.
under `universal-ctags|setting to use Universal Ctags plug-in parser:\` in gtags.conf
fixes the issue for me and ctags start using that langdef when called by gtags.
But maybe you should consider adding smth like
to gtags.conf to support arbitrary ctags options, not just --langmap and -exlude.