Document /issue_trackers/<name>/issues/<issue_name>

... routes with OpenAPI.

src/api/public/apidocs-new/OBS-v2.10.50.yaml

@@ -38,6 +38,8 @@ paths:
     $ref: 'paths/issue_trackers.yaml'
   /issue_trackers/{issue_tracker_name}:
     $ref: 'paths/issue_trackers_issue_tracker_name.yaml'
+  /issue_trackers/{issue_tracker_name}/issues/{issue_name}:
+    $ref: 'paths/issue_trackers_issue_tracker_name_issues_issue_name.yaml'
 
   /person:
     $ref: 'paths/person.yaml'

src/api/public/apidocs-new/components/parameters/issue_name.yaml

@@ -0,0 +1,7 @@
+in: path
+name: issue_name
+schema:
+  type: string
+required: true
+description: Issue name.
+example: 12345

src/api/public/apidocs-new/components/schemas/issue.yaml

@@ -0,0 +1,22 @@
+type: object
+properties:
+  created_at:
+    type: string
+    example: '2021-01-18 19:17:51 UTC'
+  updated_at:
+    type: string
+    example: '2021-01-18 19:17:51 UTC'
+  name:
+    type: string
+    example: 12345
+  tracker:
+    type: string
+    example: fate
+  label:
+    type: string
+    example: 'fate#12345'
+  url:
+    type: string
+    example: 'https://features.opensuse.org/12345'
+xml:
+  name: issue

src/api/public/apidocs-new/paths/issue_trackers_issue_tracker_name_issues_issue_name.yaml

@@ -0,0 +1,34 @@
+get:
+  summary: Show an issue of an issue tracker.
+  description: Show an issue of an issue tracker.
+  security:
+    - basic_authentication: []
+  parameters:
+    - $ref: '../components/parameters/issue_name.yaml'
+  responses:
+    '200':
+      description: |
+        Issue definition.
+
+        XML Schema used for body validation: [issue.rng](../schema/issue.rng)
+      content:
+        application/xml; charset=utf-8:
+          schema:
+            $ref: '../components/schemas/issue.yaml'
+    '401':
+      $ref: '../components/responses/unauthorized.yaml'
+    '404':
+      description: |
+        Not Found.
+
+        XML Schema used for body validation: [status.xsd](../schema/status.xsd)
+      content:
+        application/xml; charset=utf-8:
+          schema:
+            $ref: '../components/schemas/api_response.yaml'
+          example:
+            code: issue_tracker_not_found
+            summary: Error: Issue Tracker 'foo' not found.
+  tags:
+    - Issue Trackers
+