Fix extensions handling for allOf with single schema (#15632)

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -3993,6 +3993,9 @@ public class DefaultCodegen implements CodegenConfig {
             if (p.getWriteOnly() != null) {
                 property.isWriteOnly = p.getWriteOnly();
             }
+            if (original.getExtensions() != null) {
+                property.getVendorExtensions().putAll(original.getExtensions());
+            }
         }
 
         // set the default value

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

@@ -347,6 +347,11 @@ public class TestUtils {
                     .containsWithName("javax.persistence.Transient")
                     .toProperty()
                 .toType();
+
+        JavaFileAssert.assertThat(java.nio.file.Paths.get(baseOutputPath + "/CompanyDto.java"))
+            .hasProperty("priceCategory")
+                .assertPropertyAnnotations()
+                .containsWithNameAndAttributes("IgnoreForRoles", ImmutableMap.of("value", "\"MEDIA_ADMIN\""));
     }
 
     public static ModelsMap createCodegenModelWrapper(CodegenModel cm) {

modules/openapi-generator/src/test/resources/3_0/issue_11772.yml

@@ -65,6 +65,8 @@ paths:
           description: A list resource collection of Employees.
       operationId: getEmployees
       summary: List all employees.
+  /company:
+    summary: Represents a Company
 components:
   schemas:
     EmployeeEntity:
@@ -277,3 +279,20 @@ components:
           description: Role that the employee is billed for on the project..
           type: string
           example: Consultant
+    CompanyDto:
+      type: object
+      properties:
+        priceCategory:
+          description: The price category
+          nullable: true
+          x-field-extra-annotation: '@IgnoreForRoles("MEDIA_ADMIN")'
+          allOf:
+            - $ref: '#/components/schemas/SamplingPriceCategoryEnum'
+
+    SamplingPriceCategoryEnum:
+      description: The price category of a sampling action
+      type: string
+      enum:
+        - FREE
+        - PRICE_TIER_1
+        - PRICE_TIER_2