Fix infinite recursion stopping too early

Author: jpfinne

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

@@ -1790,7 +1790,6 @@ private boolean hasParent(Schema parent, Schema child, String reference, Set<Sch
                 if (visitedSchemas.contains(schema)) {
                     return false;
                 }
-                visitedSchemas.add(schema);
                 if (hasParent(parent, schema, reference, visitedSchemas)) {
                     return true;
                 }