@Override
    public boolean equals(final Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        final ApiUserIdentity that = (ApiUserIdentity) o;
        return Objects.equals(userRef, that.userRef) &&
               Objects.equals(sessionId, that.sessionId);
    }
@param userUuid    The stroom_user UUID
@param subjectId   The unique ID on the IDP, i.e. the 'sub' claim
@param displayName
stroom-security/stroom-security-impl/src/main/java/stroom/security/impl/ApiUserIdentity.java