Please remove this old comment from the opennms-datasources configuration file:
- Uses C3P0 (http://sourceforge.net/projects/c3p0/).
This data source is not XA-capable but is available because it was the default
datasource on OpenNMS 1.12. It is well tested as a reliable database pool.
- Uses HikariCP (http://brettwooldridge.github.io/HikariCP/), a lightweight and extremely fast connection pool