Go generate all of with multiple ref and discriminator (#18390)

* feat(go): Generate compiling stubs for allOf with multiple refs and discriminator

* feat(go): Generate compiling stubs for allOf with multiple refs and discriminator

* feat(go): Generate compiling stubs for allOf with multiple refs and discriminator

Author: rikotsev

modules/openapi-generator/src/main/resources/go/model_simple.mustache

@@ -3,16 +3,14 @@ var _ MappedNullable = &{{classname}}{}
 
 // {{classname}} {{{description}}}{{^description}}struct for {{{classname}}}{{/description}}
 type {{classname}} struct {
-{{#parent}}
-{{^isMap}}
+{{#parentModel.name}}
 {{^isArray}}
-	{{{parent}}}
+	{{{parentModel.name}}}
 {{/isArray}}
-{{/isMap}}
 {{#isArray}}
-	Items {{{parent}}}
+	Items {{{parentModel.name}}}
 {{/isArray}}
-{{/parent}}
+{{/parentModel.name}}
 {{#vars}}
 {{^-first}}
 {{/-first}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/go/GoClientCodegenTest.java

@@ -291,6 +291,27 @@ public void verifyApiTestWithNullResponse() throws IOException {
                 "httpRes, err := apiClient.PetAPI.PetDelete(context.Background()).Execute()");
     }
 
+    @Test
+    public void verifyApiWithAllOfMultipleRefAndDiscriminator() throws IOException {
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("go")
+                .setGitUserId("OpenAPITools")
+                .setGitRepoId("openapi-generator")
+                .setInputSpec("src/test/resources/3_0/go/allof_multiple_ref_and_discriminator.yaml")
+                .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(configurator.toClientOptInput()).generate();
+        files.forEach(File::deleteOnExit);
+
+        TestUtils.assertFileExists(Paths.get(output + "/model_final_item.go"));
+        TestUtils.assertFileContains(Paths.get(output + "/model_final_item.go"),
+                "BaseItem");
+    }
+
     @Test
     public void testAdditionalPropertiesWithGoMod() throws Exception {
         File output = Files.createTempDirectory("test").toFile();

modules/openapi-generator/src/test/resources/3_0/go/allof_multiple_ref_and_discriminator.yaml

@@ -0,0 +1,54 @@
+openapi: 3.0.0
+info:
+  title: Test
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    FinalItem:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/BaseItem'
+        - $ref: '#/components/schemas/AdditionalData'
+    BaseItem:
+      type: object
+      properties:
+        title:
+          type: string
+        type:
+          type: string
+          enum:
+            - FINAL
+          example: FINAL
+      discriminator:
+        propertyName: type
+        mapping:
+          FINAL: '#/components/schemas/FinalItem'
+      required:
+        - title
+        - type
+    AdditionalData:
+      type: object
+      properties:
+        prop1:
+          type: string
+        quantity:
+          type: integer
+          format: int32
+          example: 1
+          minimum: 1
+        unitPrice:
+          type: number
+          format: double
+          example: 9.99
+          minimum: 0.0
+        totalPrice:
+          type: number
+          format: double
+          example: 9.99
+          minimum: 0.0
+      required:
+        - prop1
+        - quantity
+        - unitPrice
+        - totalPrice