Eclipse associating *.mod files with DTD, validation fails for Jetty mod file

Question

I recently brought an existing maven project into Eclipse 2020-03. The project contains a jetty folder which itself contains a file:

modules/somefile.mod

The *.mod file pattern seems to be associated with the DTD content type, and this association is "locked". Because my file is not a DTD, it fails the validation.
Eclipse's Bugzilla lists a 7-year old bug, Bug 420688, which describes this problem, but the workarounds there don't seem to work for me.
The validation error I get is

The markup declarations contained or pointed to by the document type declaration must be well-formed.

Is there a way to

1. Disable the validation of this particular file, or preferably
2. Disassociate it from the DTD content type?

Thanks for any advice or direction.