@Override
  public List<NetworkSend> completedSends() {
    return this.completedSends;
  }
Returns {@code true} if channel is ready to send or receive data, {@code false} otherwise
@param connectionId upon which readiness is checked for
@return true if channel is ready to accept reads/writes, false otherwise
ambry-network/src/main/java/com/github/ambry/network/Selector.java