Implemented the GET /users/{username}/collection/folders endpoints for the Open API specification document in the library target.

Sources/DiscogsService/openapi.yaml

@@ -1060,6 +1060,47 @@ paths:
           $ref: '#/components/responses/NotFound'
         '500':
           $ref: '#/components/responses/InternalError'
+  /users/{username}/collection/folders:
+    get:
+      tags:
+        - User Collection
+      summary: Get collection folder of a user.
+      description: |
+        Retrieves a list of folders in a collection of a user. 
+        
+        In case the collection has been made private by its owner, authentication as the collection owner is required. Otherwise, only folder `ID 0`` (the “All” folder) will be visible only if the requested collection of a user is public.
+      operationId: getUserCollectionFolders
+      parameters:
+        - $ref: '#/components/parameters/Username'
+      responses:
+        '200':
+          description: Successfully retrieved all the collection folders by a user.
+          headers:
+            X-Discogs-RateLimit:
+              $ref: '#/components/headers/RateLimit'
+            X-Discogs-RateLimit-Used:
+              $ref: '#/components/headers/RateLimitUsed'
+            X-Discogs-RateLimit-Remaining:
+              $ref: '#/components/headers/RateLimitRemaining'
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  pagination:
+                    $ref: '#/components/schemas/Pagination'
+                  folders:
+                    description: A list of collection folders of a user.
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/Folder'
+                required:
+                  - pagination
+                  - folders
+        '404':
+          $ref: '#/components/responses/NotFound'
+        '500':
+          $ref: '#/components/responses/InternalError'
 components:
   headers:
     Link:
@@ -1558,6 +1599,30 @@ components:
         - NZD
         - SEK
         - ZAR
+    Folder:
+      description: A type that represents a collection folder of a user.
+      type: object
+      properties:
+        id:
+          description: An identifier of a collection folder.
+          type: integer
+          readOnly: true
+        name:
+          description: A name of a collection folder.
+          type: string
+        count:
+          description: A number of items a collection folder contains.
+          type: integer
+        resource_url:
+          description: A URI resource of a collection folder.
+          type: string
+          format: uri
+          readOnly: true
+      required:
+        - count
+        - id
+        - name
+        - resource_url
     Identifier:
       description: A type that represents an identifier.
       type: object