@Override
    public String toString() {
        return "UserIdentityImpl{" +
               "updatableToken=" + updatableToken +
               ", userRef='" + userRef + '\'' +
               ", isInSession='" + isInSession() + '\'' +
               '}';
    }
@return True if this {@link UserIdentity} has a session and is an attribute value in that session
stroom-security/stroom-security-impl/src/main/java/stroom/security/impl/UserIdentityImpl.java