How do you check when a key is mapped in vim?

Question

I have a few mappings in vim for moving between splits set in my .vimrc,

nnoremap <C-j> <C-w>j
nnoremap <C-k> <C-w>k
nnoremap <C-h> <C-w>h
nnoremap <C-l> <C-w>l

All of these work except for <C-j>, which I suspect is being remapped in one of my plugins. I'd like to find out where, but I'm not sure how. Is there a way to find "where was <C-j> last mapped?"

Answer 1

:verbose nnoremap <c-j>

should help.