How to enable TLS on MongoDB operator without requiring client certificates

I am very new to the operator and only understand the basic features. I am trying to work out a way to enable TLS on the operator without the need of client certificates… I tried to modify the cr.yaml file, specifically the section. Reference: I noticed that, the changes are not reflected onto the pods. ie, previously the sslMode was configured to be preferSSL, which I am guessing is the default mode. Evena fter applying above mentioned changes, it is not accepting the connection. I also want to be able to enable settings like allowConnectionsWithoutCertificates. Are those possible for the operator? 
PS: I am running the pods in a GKE cluster, following the installation instructions from
Any info regarding TLS certificates no matter how basic is also welcome.