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

Sources/DiscogsService/openapi.yaml

@@ -1453,6 +1453,51 @@ paths:
           $ref: '#/components/responses/NotFound'
         '500':
           $ref: '#/components/responses/InternalError'
+  /users/{username}/collection/fields:
+    get:
+      tags:
+        - User Collection
+      summary: Get a list of custom fields defined by a user.
+      description: |
+        Retrieves a list of collection notes fields defined by a user. 
+        
+        These fields are available on every release in a collection. In case a collection has been made private by its owner, then the endpoints requires authentication as the collection owner. Otherwise only public custom fields will be visible.
+      operationId: getCustomFields
+      parameters:
+        - $ref: '#/components/parameters/Username'
+      security:
+        - ConsumerKeySecret: []
+        - UserToken: []
+        - OAuth: []
+      responses:
+        '200':
+          description: Successfully retrieved a list of custom fields defined 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:
+                description: A type that contains a list of retrieved custom fields of a user.
+                type: object
+                properties:
+                  fields:
+                    description: A list of custom fields.
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/CustomField'
+                required:
+                  - fields
+        '403':
+          $ref: '#/components/responses/NotAccessable'
+        '404':
+          $ref: '#/components/responses/NotFound'
+        '500':
+          $ref: '#/components/responses/InternalError'
 components:
   headers:
     Link:
@@ -1978,6 +2023,45 @@ components:
         - NZD
         - SEK
         - ZAR
+    CustomField:
+      description: A type that represents a custom field.
+      type: object
+      properties:
+        id:
+          description: An identifier of a custom field.
+          type: integer
+          readOnly: true
+        name:
+          description: A name of a custom field.
+          type: string
+        position:
+          description: A position of a custom field.
+          type: integer
+          minimum: 1
+        public:
+          description: A flag that indicates whether a custom field is public or not.
+          type: boolean
+        type:
+          description: A type of a custom field.
+          type: string
+          enum:
+            - dropdown
+            - textarea
+        lines:
+          description: A number of lines of content to allow for a custom field of a textarea type.
+          type: integer
+          minimum: 1
+        options:
+          description: A list of options to display, in case the field is of dropdown type.
+          type: array
+          items:
+            type: string
+      required:
+        - id
+        - name
+        - position
+        - public
+        - type
     Folder:
       description: A type that represents a collection folder of a user.
       type: object