In https://access.redhat.com/documentation/en-us/red_hat_jboss_amq/7.0/html-single/using_amq_broker/#configuring_persistence, section 5.2.5. Message Persistence says

When persistence-enabled is true the journal persists to the directories specified and using the specified journal type of NIO. Alternative journal types are ASYNCIO and JDBC.

In fact, JDBC is not a valid value for the <journal-type>. JDBC is configured by having a <database-store> configured in the broker.xml file. If a <database-store> is configured, then all journal configuration is ignored and database is used instead. (My impression)

Additionally, in released AMQ 7 Broker 7.0.2, a comment in etc/broker.xml lists valid values for <journal-type> to be "ASYNCIO", "NIO" and "MAPPED". The "MAPPED" option is undocumented in downstream. (Something fnigro developed.)