Connection to postgres on ssl

I’m trying to deploy camunda on kubernetes using a postgres backend.
Our postgres cluster requires ssl connections.

The environment variables I’m passing in look like this:

env:
- name: DB_DRIVER
  value: org.postgresql.Driver
- name: DB_URL
  value: "jdbc:postgresql://<POSTGRES_FQDN >:5432/camunda&ssl=true"              
- name: DB_USERNAME
  value: "camunda"
- name: DB_PASSWORD
  valueFrom:
    secretKeyRef:
      name: camunda-secrets
      key: DB_PASSWORD

However it’s failing to connect with:

04-Oct-2018 09:51:04.345 SEVERE [main] org.apache.tomcat.jdbc.pool.ConnectionPool.init Unable to create initial connections of pool.
org.postgresql.util.PSQLException: FATAL: SSL connection is required. Please specify SSL options and retry.

Camunda seems to be ingnoreing ssl=true in the connection string.
Is something else required to enable ssl?

I haven’t been able to find anything in the docs.