There is currently a karaf feature in the TransportPCE project that is useless, does absolutely nothing, and which should therefore be removed: odl-transportpce-swagger.
This feature was created several years ago to try to enable swagger for developers when it was no longer operational from upstream dependencies.
But this attempt of trick has never worked.

Today, swagger is functional without having to activate anything via the following url:

http://<server>:8181/openapi/explorer/index.html

This feature should simply be deleted.