Reimplement support for enums in a sane way

[gavinking]

The implementation of enum support in Hibernate involves a UserType and two BasicValueConverters. This was never a very sensible way to do it, and dates back, I assume, to the time when Hibernate Annotations and Hibernate EntityManager were separate projects.

This is extremely painful to deal with in general, and in particular it makes it almost impossible to implement support for PostgreSQL enum types.

We need to fix this.

[gavinking]

Related: HHH-16125 , #6232

[gavinking]

This is now fixed. @sebersole got rid of the UserType, and I got rid of the value converters. There's still a deprecated EnumType left over for certain legacy stuff (hbm.xml) but it's much simplified.

The real work is now handled by EnumJavaType, PostgreSQLEnumJdbcType, and MySQLEnumJdbcType. This follows the usual pattern of "compositional" basic types.

[nstdio]

Sorry to post a question in closed discussion.
I wonder is there a way to explicitly specify PostgreSQL enum type? Currently implementation consider Java enum type name as PostgreSQL enum type name. Has been comment addressed?

[gavinking]

It is this open issue: https://hibernate.atlassian.net/browse/HHH-16536