Authentication plugin sha256_password is missing from v3

The sha256_password authentication plugin is missing from the 3.0 rewrite. Please could this be added again, or please could the documentation be updated to clarify that it's only available for the 2.x client?

E.g.:

• https://mariadb.com/kb/en/about-mariadb-connector-j/#authentication-service
• https://mariadb.com/kb/en/authentication-plugin-sha-256/#using-the-plugin-with-mariadb-connectorj