refactor: update getDiscriminatorSchemaDeep method to accept a List for visited schemas

Author: Ignacio-Vidal

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

@@ -74,7 +74,7 @@ static Optional<String> getDiscriminatorPropertyTypeFromChildren(OpenAPI openAPI
             if (resolved == null) {
                 continue;
             }
-            Schema discSchema = getDiscriminatorSchemaDeep(openAPI, resolved, discriminatorPropertyName);
+            Schema discSchema = getDiscriminatorSchemaDeep(openAPI, resolved, discriminatorPropertyName, new ArrayList<>());
             if (discSchema != null && discSchema.get$ref() != null) {
                 return Optional.ofNullable(ModelUtils.getSimpleRef(discSchema.get$ref()));
             }
@@ -90,16 +90,10 @@ static Optional<String> getDiscriminatorPropertyTypeFromChildren(OpenAPI openAPI
      * @param openAPI           the OpenAPI specification, used to resolve referenced allOf members.
      * @param schema            The schema to inspect.
      * @param discriminatorName The name of the discriminator property.
+     * @param visited           A list of schemas already visited in the recursion, to avoid infinite loops.
+     * @return The discriminator property schema, or null if not found.
      */
-    static Schema getDiscriminatorSchemaDeep(OpenAPI openAPI, Schema schema, String discriminatorName) {
-        return getDiscriminatorSchemaDeep(openAPI, schema, discriminatorName, new ArrayList<>());
-    }
-
-    /**
-     * @param visited the schemas already visited on the current allOf descent, used to guard against a
-     *                cyclic allOf composition recursing infinitely.
-     */
-    private static Schema getDiscriminatorSchemaDeep(OpenAPI openAPI, Schema schema, String discriminatorName, ArrayList<Schema> visited) {
+    static Schema getDiscriminatorSchemaDeep(OpenAPI openAPI, Schema schema, String discriminatorName, List<Schema> visited) {
         for (Schema s : visited) {
             if (s == schema) {
                 return null;