fix: add support for discriminator in oneOf schemas and update model imports

Author: GregoryMerlet

modules/openapi-generator/src/main/resources/typescript-fetch/modelOneOf.mustache

@@ -1,13 +1,13 @@
 {{#hasImports}}
-{{#imports}}
+{{#oneOfModels}}
 import type { {{{.}}} } from './{{.}}{{importFileExtension}}';
 import {
     instanceOf{{{.}}},
     {{{.}}}FromJSON,
     {{{.}}}FromJSONTyped,
     {{{.}}}ToJSON,
 } from './{{.}}{{importFileExtension}}';
-{{/imports}}
+{{/oneOfModels}}
 
 {{/hasImports}}
 {{>modelOneOfInterfaces}}

modules/openapi-generator/src/test/resources/3_0/typescript-fetch/oneOf.yaml

@@ -25,6 +25,16 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/TestArrayResponse'
+  /test-discriminator:
+    get:
+      operationId: testDiscriminator
+      responses:
+        200:
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TestDiscriminatorResponse'
 components:
   schemas:
     TestArrayResponse:
@@ -38,6 +48,15 @@ components:
         - type: array
           items:
             type: string
+    TestDiscriminatorResponse:
+      discriminator:
+        propertyName: discriminatorField
+        mapping:
+          optionOne: "#/components/schemas/OptionOne"
+          optionTwo: "#/components/schemas/OptionTwo"
+      oneOf:
+        - $ref: "#/components/schemas/OptionOne"
+        - $ref: "#/components/schemas/OptionTwo"
     TestResponse:
       oneOf:
         - $ref: "#/components/schemas/TestA"
@@ -56,4 +75,22 @@ components:
         bar:
           type: string
       required:
-        - bar
+        - bar
+    OptionOne:
+      type: object
+      properties:
+        discriminatorField:
+          enum:
+            - "optionOne"
+          type: string
+      required:
+        - discriminatorField
+    OptionTwo:
+      type: object
+      properties:
+        discriminatorField:
+          enum:
+            - "optionTwo"
+          type: string
+      required:
+        - discriminatorField