@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    context.getSerializer().writeObject(memberID, out);
    if (rejectedCoordinators != null) {
      out.writeInt(rejectedCoordinators.size());
      for (ID mbr : rejectedCoordinators) {
        context.getSerializer().writeObject(mbr, out);
      }
    } else {
      out.writeInt(0);
    }
    out.writeInt(lastViewId);
    out.writeInt(requestId);
    StaticSerialization.writeString(dhalgo, out);
    StaticSerialization.writeByteArray(myPublicKey, out);
  }
FindCoordinatorRequest is a message intended to be sent via a TcpClient to a Locator.
It is used during startup to discover the cluster's membership coordinator.
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/locator/FindCoordinatorRequest.java