How to upload an origin file in opj extension in MediaWiki

On Mediawiki upload module checks mime types.

OPJ extension is blocked  - actually not listed

To upload opj, edit $mediawiki/includes/mime.types

Near the end search 

chemical/x-mdl-rgfile rg

Then add opj at the end of the line like

chemical/x-mdl-rgfile rg opj

In this way you can upload opj files.