In the commit #f6aa8ab was added the class MariaDB10Dialect which add few new functions:
What is funny is that those functions was actually backported to MariaDB from MySQL but the MySQL Dialect doesn't have them.
So I created a small PR to backport those functions from MariaDB dialect to MySQL dialect.
weight_string, to_base64, from_base64: was added in MySQL 5.6 but we have only 5.7 dialect so I added the function there.
regexp_replace, regexp_instr, regexp_substr: was added in MySQL 8