@Override
    default String getUserIdentityForAudit() {
        final String subjectId = getSubjectId();
        final String displayName = getDisplayName();
        // GWT so no Objects.requireNonNullElse()
        if (displayName != null) {
            return displayName;
        } else {
            return subjectId;
        }
    }
@return The user's full name if known, e.g. 'Joe Bloggs'.
stroom-security/stroom-security-api/src/main/java/stroom/security/api/UserIdentity.java