class DocumentReference {

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (!(o instanceof DocumentReference)) {
      return false;
    }

    DocumentReference that = (DocumentReference) o;

    return key.equals(that.key) && firestore.equals(that.firestore);
  }

    DocumentReference(DocumentKey key, FirebaseFirestore firestore);

}