Deprecate /groups/:id/runners?type=project_type

This endpoint always returned an empty collection and the behavior was
undefined.

Changelog: deprecated

data/deprecations/14-8-runner-api-project_type-breaking-change.yml

+- name: "REST API endpoint to list group runners no longer accepts `project_type` value for `type` argument"
+  announcement_milestone: "14.8"
+  announcement_date: "2022-02-22"
+  removal_milestone: "15.0"
+  removal_date: "2022-05-22"
+  breaking_change: true
+  reporter: pedropombeiro
+  body: |
+    The `GET /groups/:id/runners?type=project_type` endpoint will be removed in GitLab 15.0. The endpoint always returned an empty collection.
+  stage: Verify
+  tiers: [Core, Premium, Ultimate]
+  issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/351466
+  documentation_url: https://docs.gitlab.com/ee/api/runners.html
+  image_url: # (optional) This is a link to a thumbnail image depicting the feature
+  video_url: # (optional) Use the youtube thumbnail URL with the structure of https://img.youtube.com/vi/UNIQUEID/hqdefault.jpg

doc/api/runners.md

@@ -576,13 +576,13 @@ GET /groups/:id/runners/all?paused=true
 GET /groups/:id/runners?tag_list=tag1,tag2
 ```
 
-| Attribute  | Type           | Required | Description                                                                                                                                                                           |
-|------------|----------------|----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `id`       | integer        | yes      | The ID of the group owned by the authenticated user                                                                                                                                   |
-| `type`     | string         | no       | The type of runners to show, one of: `instance_type`, `group_type`, `project_type`                                                                                                    |
-| `status`   | string         | no       | The status of runners to show, one of: `online` and `offline`. `active` and `paused` are also possible values which were deprecated in GitLab 14.8 and will be removed in GitLab 15.0 |
-| `paused`   | boolean        | no       | Whether to include only runners that are accepting or ignoring new jobs                                                                                                               |
-| `tag_list` | string array   | no       | List of the runner's tags                                                                                                                                                             |
+| Attribute  | Type           | Required | Description                                                                                                                                                                                                           |
+|------------|----------------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `id`       | integer        | yes      | The ID of the group owned by the authenticated user                                                                                                                                                                   |
+| `type`     | string         | no       | The type of runners to show, one of: `instance_type`, `group_type`, `project_type`. The `project_type` value is [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/351466) and will be removed in GitLab 15.0 |
+| `status`   | string         | no       | The status of runners to show, one of: `online` and `offline`. `active` and `paused` are also possible values which were deprecated in GitLab 14.8 and will be removed in GitLab 15.0                                 |
+| `paused`   | boolean        | no       | Whether to include only runners that are accepting or ignoring new jobs                                                                                                                                               |
+| `tag_list` | string array   | no       | List of the runner's tags                                                                                                                                                                                             |
 
 ```shell
 curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/groups/9/runners"

doc/update/deprecations.md

@@ -777,6 +777,18 @@ When checking for active runners, specify `paused=false`.
 
 **Planned removal milestone: 15.0 (2022-05-22)**
 
+### REST API endpoint to list group runners no longer accepts `project_type` value for `type` argument
+
+WARNING:
+This feature will be changed or removed in 15.0
+as a [breaking change](https://docs.gitlab.com/ee/development/contributing/#breaking-changes).
+Before updating GitLab, review the details carefully to determine if you need to make any
+changes to your code, settings, or workflow.
+
+The `GET /groups/:id/runners?type=project_type` endpoint will be removed in GitLab 15.0. The endpoint always returned an empty collection.
+
+**Planned removal milestone: 15.0 (2022-05-22)**
+
 ### REST and GraphQL API Runner usage of `active` replaced by `paused`
 
 WARNING:

spec/requests/api/ci/runners_spec.rb

@@ -1048,6 +1048,7 @@ RSpec.describe API::Ci::Runners do
           ])
         end
 
+        # TODO: Remove in %15.0 (https://gitlab.com/gitlab-org/gitlab/-/issues/351466)
         it 'returns empty result when type does not match' do
           get api("/groups/#{group.id}/runners?type=project_type", user)