The following is the output from the HATEOAS API for Katello. 

[{"href":"/api/systems/","rel":"systems"},{"href":"/api/providers/","rel":"providers"},{"href":"/api/templates/","rel":"templates"},{"href":"/api/organizations/","rel":"organizations"},{"href":"/api/changesets/","rel":"changesets"},{"href":"/api/products/","rel":"products"},{"href":"/api/repositories/","rel":"repositories"},{"href":"/api/environments/","rel":"environments"},{"href":"/api/activation_keys/","rel":"activation_keys"},{"href":"/api/packages/","rel":"packages"},{"href":"/api/errata/","rel":"errata"},{"href":"/api/distributions/","rel":"distributions"},{"href":"/api/users/","rel":"users"},{"href":"/api/tasks/","rel":"tasks"},{"href":"/api/consumers/","rel":"consumers"},{"href":"/api/entitlements/","rel":"entitlements"}]

The following hrefs are not applicable to headpin:

api/templates
api/changesets
api/repositories
api/packages
api/errata
api/distrbutions


and should be removed from this list.