@Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    WorkerRelation other = (WorkerRelation) obj;
    if (worker1 == null) {
      if (other.worker1 != null)
        return false;
    } else if (!worker1.equals(other.worker1))
      return false;
    if (worker2 == null) {
      if (other.worker2 != null)
        return false;
    } else if (!worker2.equals(other.worker2))
      return false;
    return true;
  }