Custom right using builtin:authenticate on macOS

When implementing a custom right in macOS authorizationdb, the mechanism array element builtin:authenticate is displaying the message 'Enter the name and password of a user in the "(null)" group to allow this.' on the macOS credential prompt UI popup. I am trying to find a fix to avoid the reference to null group in the message label that is displayed just above the username and password input fields. The current plist uses class as the key and value as the evaluate-mechanisms. The mechanisms array includes mechanism array with elements "builtin:login-begin", "mycustombundle:mycustompreaction", "builtin:authenticate", "mycustombundle:mycustommechanism". I have tried specifying group in the plist, have tried setting hint in the MechanismInvoke for group, username, security, authority, prompt, reason among several other hints into the context duing the execution of mycustombundle:mycustompreaction, but none seem to fix the "(null)" in the message label. Any help is greately appreciated. There is not much of any documentation for developers implementing custom authorization in macOS.