Implement referenced enum merging from oneof/anyof

Author: pieterbos

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

@@ -1367,9 +1367,6 @@ protected Schema simplifyComposedSchemaWithEnums(Schema schema, List<Object> sub
             }
 
             Schema subSchema = ModelUtils.getReferencedSchema(openAPI, (Schema) item);
-            if(subSchema.get$ref() != null) {
-                return schema;
-            }
 
             // Check if this sub-schema has an enum (with one or more values)
             if (subSchema.getEnum() == null || subSchema.getEnum().isEmpty()) {

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

@@ -187,6 +187,13 @@ public void testSimplifyOneOfAnyOfEnum() throws Exception {
         assertEquals(anyOfParam.getSchema().getType(), "string");
         assertEquals(anyOfParam.getSchema().getEnum(), Arrays.asList("anyof 1", "anyof 2"));
 
+        Schema combinedRefsEnum = openAPI.getComponents().getSchemas().get("combinedRefsEnum");
+
+        assertEquals(anyOfParam.getSchema().getType(), "string");
+        assertNull(combinedRefsEnum.get$ref());
+        assertEquals(combinedRefsEnum.getEnum(), Arrays.asList("A", "B", "C", "D"));
+        assertNull(combinedRefsEnum.getOneOf());
+
         // Test with rule disabled
         OpenAPI openAPI2 = TestUtils.parseSpec("src/test/resources/3_0/simplifyoneOfWithEnums_test.yaml");
         Map<String, String> options2 = new HashMap<>();
@@ -208,6 +215,7 @@ public void testSimplifyOneOfAnyOfEnum() throws Exception {
         Parameter anyOfParam2 = openAPI2.getPaths().get("/test").getGet().getParameters().get(1);
         assertNull(anyOfParam2.getSchema().getOneOf());
         assertNull(anyOfParam2.getSchema().getEnum());
+
     }
 
     @Test

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

@@ -20,6 +20,20 @@ components:
           enum: [1]
         - title: inactive_pending
           enum: [2, 3]
+    enum1:
+      type: string
+      enum:
+        - A
+        - B
+    enum2:
+      type: string
+      enum:
+        - C
+        - D
+    combinedRefsEnum:
+      oneOf:
+        - $ref: '#/components/schemas/enum1'
+        - $ref: '#/components/schemas/enum2'
 paths:
   /test:
     get: