@Override
  public int hashCode() {
    return Objects.hash(senderId, view, registrants, requestId);
  }
When the response comes from a locator via TcpClient this will return the locators member ID.
If the locator hasn't yet joined this may be null.
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/locator/FindCoordinatorResponse.java