We should not need to configure DSpace itself with the brand of DBMS to be used. We can probe that out of the driver at startup, and get rid of a configuration property. This also eliminates confusion with -Ddb.name, a completely separate configuration item for our Maven projects which is used to pull in the Oracle driver at build time.
I've tested java.sql.Connection.getMetaData().getDatabaseProductName() with PostgreSQL, H2 and Oracle JDBC drivers, and it returns "PostgreSQL", "H2" resp. "Oracle". Using this instead of manual configuration would eliminate a source of potential error.