api-8.x-1.x-dev/api.links.action.yml

project.add_form:
  route_name: entity.project.add_form
  title: 'Add project'
  appears_on:
    - entity.project.collection
branch.add_form:
  route_name: entity.branch.add_form
  title: 'Add branch'
  appears_on:
    - entity.branch.collection
php_branch.add_form:
  route_name: entity.php_branch.add_form
  title: 'Add PHP branch'
  appears_on:
    - entity.php_branch.collection
external_branch.add_form:
  route_name: entity.external_branch.add_form
  title: 'Add External branch'
  appears_on:
    - entity.external_branch.collection