Add group milestones API endpoint

2 files changed, 122 insertions, 1 deletions

diff --git a/doc/api/README.md b/doc/api/README.md
index 95e7a457848..a888c0ebb4e 100644
--- a/doc/api/README.md
+++ b/doc/api/README.md
@@ -29,7 +29,8 @@ following locations:
 - [Keys](keys.md)
 - [Labels](labels.md)
 - [Merge Requests](merge_requests.md)
-- [Milestones](milestones.md)
+- [Project milestones](milestones.md)
+- [Group milestones](group_milestones.md)
 - [Namespaces](namespaces.md)
 - [Notes](notes.md) (comments)
 - [Notification settings](notification_settings.md)
diff --git a/doc/api/group_milestones.md b/doc/api/group_milestones.md
new file mode 100644
index 00000000000..086fba7e91d
--- /dev/null
+++ b/doc/api/group_milestones.md
@@ -0,0 +1,120 @@
+# Group milestones API
+
+## List group milestones
+
+Returns a list of group milestones.
+
+```
+GET /groups/:id/milestones
+GET /groups/:id/milestones?iids=42
+GET /groups/:id/milestones?iids[]=42&iids[]=43
+GET /groups/:id/milestones?state=active
+GET /groups/:id/milestones?state=closed
+GET /groups/:id/milestones?search=version
+```
+
+Parameters:
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `id` | integer/string | yes | The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user |
+| `iids` | Array[integer] | optional | Return only the milestones having the given `iids` |
+| `state` | string | optional | Return only `active` or `closed` milestones` |
+| `search` | string | optional | Return only milestones with a title or description matching the provided string |
+
+```bash
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/5/milestones
+```
+
+Example Response:
+
+```json
+[
+  {
+    "id": 12,
+    "iid": 3,
+    "group_id": 16,
+    "title": "10.0",
+    "description": "Version",
+    "due_date": "2013-11-29",
+    "start_date": "2013-11-10",
+    "state": "active",
+    "updated_at": "2013-10-02T09:24:18Z",
+    "created_at": "2013-10-02T09:24:18Z"
+  }
+]
+```
+
+
+## Get single milestone
+
+Gets a single group milestone.
+
+```
+GET /groups/:id/milestones/:milestone_id
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user
+- `milestone_id` (required) - The ID of the group milestone
+
+## Create new milestone
+
+Creates a new group milestone.
+
+```
+POST /groups/:id/milestones
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user
+- `title` (required) - The title of an milestone
+- `description` (optional) - The description of the milestone
+- `due_date` (optional) - The due date of the milestone
+- `start_date` (optional) - The start date of the milestone
+
+## Edit milestone
+
+Updates an existing group milestone.
+
+```
+PUT /groups/:id/milestones/:milestone_id
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user
+- `milestone_id` (required) - The ID of a group milestone
+- `title` (optional) - The title of a milestone
+- `description` (optional) - The description of a milestone
+- `due_date` (optional) - The due date of the milestone
+- `start_date` (optional) - The start date of the milestone
+- `state_event` (optional) - The state event of the milestone (close|activate)
+
+## Get all issues assigned to a single milestone
+
+Gets all issues assigned to a single group milestone.
+
+```
+GET /groups/:id/milestones/:milestone_id/issues
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user
+- `milestone_id` (required) - The ID of a group milestone
+
+## Get all merge requests assigned to a single milestone
+
+Gets all merge requests assigned to a single group milestone.
+
+```
+GET /groups/:id/milestones/:milestone_id/merge_requests
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user
+- `milestone_id` (required) - The ID of a group milestone