get_keywords

Look up keywords for for desktop id or file path @id. The keywords will be an amalgamation of the X-GNOME-Keywords and X-AppInstall-Keywords fields from the .desktopfile. Returns null if id is not found. This method will do sync IO if the desktop file for @id is not already cached. So if you are living in an async world you must first do an async call to lookup_async(id) before calling this method, in which case no sync io will be done.