Such configuration only applies to Guice wiring.
You are encouraged to contribute by developing a new backend guice module. Have a look to the james-server-cassandra-guice artifact. This can easily be done as a third party application.
We provide a tested configuration for docker environment, for each Guice artifact, which can be a good base for your own configuration.
You can/must configure James for the following:
See also more specific configurations related to TLS, Sieve and Antispam.