To set the "hibernate.connection.isolation" property when using the Hikari connection pool, I have to use the full name of the field as defined on the JDBC Connection class (like "TRANSACTION_READ_COMMITTED", while the Hibernate documentation (and as other connection pools implement it) described that we need to express this in numeric form.

It would probably be nice to accept "READ_COMMITTED" as well, but it should at least accept the expected numeric format.