There are complex uses cases that require external configuration files provided by configmaps or secrets.

If a reference to those existing configmap/secret resources is included in the CustomResource, the operator could mount them into the POD. Once mounted, they could be accessed by custom scripts during the initialization process of the broker, applying configuration changes or whatever may be needed.

Including confimaps or secrets in the custom resource should be optional. If they are not defined, the operator won't mount anything.