fix null type check when simplifying any type (#18504)

Author: wing328

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

@@ -943,7 +943,13 @@ private Schema processSimplifyOneOf(Schema schema) {
             if (oneOfSchemas.size() == 6) {
                 TreeSet<String> ts = new TreeSet<>();
                 for (Schema s: oneOfSchemas) {
-                    ts.add(ModelUtils.getType(s));
+                    s = ModelUtils.getReferencedSchema(openAPI, s);
+                    String type = ModelUtils.getType(s);
+                    if (type == null) {
+                        LOGGER.debug("Error null type found in schema when simplifying any type with 6 sub-schemas: {}", s);
+                    } else {
+                        ts.add(type);
+                    }
                 }
 
                 if (ts.equals(anyTypeTreeSet)) {
@@ -1068,7 +1074,13 @@ private Schema processSimplifyAnyOf(Schema schema) {
             if (anyOfSchemas.size() == 6) {
                 TreeSet<String> ts = new TreeSet<>();
                 for (Schema s: anyOfSchemas) {
-                    ts.add(ModelUtils.getType(s));
+                    s = ModelUtils.getReferencedSchema(openAPI, s);
+                    String type = ModelUtils.getType(s);
+                    if (type == null) {
+                        LOGGER.debug("Error null type found in schema when simplifying any type with 6 sub-schemas: {}", s);
+                    } else {
+                        ts.add(type);
+                    }
                 }
 
                 if (ts.equals(anyTypeTreeSet)) {

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

@@ -178,6 +178,9 @@ public void testOpenAPINormalizerSimplifyOneOfAnyOf() {
         Schema schema13 = openAPI.getComponents().getSchemas().get("OneOfAnyType");
         assertEquals(schema13.getOneOf().size(), 6);
 
+        Schema schema15 = openAPI.getComponents().getSchemas().get("AnyOfAnyTypeWithRef");
+        assertEquals(schema15.getAnyOf().size(), 6);
+
         Map<String, String> options = new HashMap<>();
         options.put("SIMPLIFY_ONEOF_ANYOF", "true");
         OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
@@ -216,6 +219,9 @@ public void testOpenAPINormalizerSimplifyOneOfAnyOf() {
         assertEquals(schema14.getOneOf(), null);
         assertEquals(schema14.getType(), null);
 
+        Schema schema16 = openAPI.getComponents().getSchemas().get("AnyOfAnyTypeWithRef");
+        assertEquals(schema16.getAnyOf(), null);
+        assertEquals(schema16.getType(), null);
     }
 
     @Test

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

@@ -103,6 +103,17 @@ components:
         - type: string
         - type: number
         - type: integer
+    AnyOfAnyTypeWithRef:
+      anyOf:
+        - type: boolean
+        - type: array
+          items: { }
+        - type: object
+        - type: string
+        - type: number
+        - $ref: '#/components/schemas/IntegerRef'
+    IntegerRef:
+      type: integer
     OneOfAnyType:
       oneOf:
         - type: object