MongoDB 3.6 introduced Authentication Restrictions ( PM-757 ). This epic included adding authenticationRestrictions info to the output of the "rolesInfo" command (and by extension, the db.getRoles() helper) if the parameter "showAuthenticationRestrictions: 1" is included in the request.

e.g.

db.getRoles({showAuthenticationRestrictions: 1});
db.runCommand({rolesInfo:1, showAuthenticationRestrictions: 1});

The current manual pages for these commands do not list this new argument.