public String getDisplayName() {
        return displayName;
    }
@return An optional, potentially non-unique, more human friendly username for the user.
Will be null if this is a group or the IDP does not provide one
or one has not been set for the user.
Intended for display purposes only or to aid in identifying the user where {@code name}
is an unfriendly UUID.
stroom-core-shared/src/main/java/stroom/security/shared/User.java