/usr/lib/mime/packages/treeline is in treeline 1.4.1-1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | application/x-treeline; treeline %s; test=test "$DISPLAY" != ""; description=TreeLine Data; nametemplate=%s.trl; priority=6
|