PostgreSQL persistence opens too many connections

I am using the PostgreSQL JDBC persistence service. This works but I would like to limit the number of database connections, as the database is a small cloud instance with a low connection limit (Google Cloud SQL).

In my services/jdbc.cfg I have the line

jdbc.maximumPoolSize = 3

Despite this, openHAB always opens 10 connections to the DB. The value of maximumPoolSize seems to have no effect.

Is this unsupported or broken?

I’m using openHABian with openHAB 2.3.0 with JDBC Persistence bundle v1.12.0.