Why was the pull request for a test declined?
IMHO the change in https://github.com/hibernate/hibernate-orm/commit/29ed2592c0e04eebb598e3c80160616b4ae5f1b3 should resolve this issue.
- simpleValue.setTypeParameters( typeDef.getParameters() ); + simpleValue.setTypeParameters( (Properties) typeDef.getParameters().clone() );