gradient_server-1.0.x-dev/modules/source/source.links.action.yml

entity.source.add_form:
  route_name: entity.source.add_page
  title: 'Add Source'
  appears_on:
    - entity.source.collection
entity.source_type.add_form:
  route_name: entity.source_type.add_form
  title: 'Add Source type'
  appears_on:
    - entity.source_type.collection