It is not clear how to set com.sun.security.sasl.digest.realm property for SASL Authentication Mechanism.

How to Configure Server Security Guide
Appendix A.2.2. SASL Authentication Mechanism Properties
Property com.sun.security.sasl.digest.realm

Note: Table is ok, but I was not able to find out how set it up in other part of documentation (maybe I only missed it).

For more details how to set it please check comment here