@Override
  public void writeTo(final RLPOutput rlpOutput) {
    // RLP encode of the message data content (round identifier and prepared certificate)
    rlpOutput.startList();
    roundChangeIdentifier.writeTo(rlpOutput);

    if (preparedCertificate.isPresent()) {
      preparedCertificate.get().writeTo(rlpOutput);
    } else {
      rlpOutput.writeNull();
    }
    rlpOutput.endList();
  }
Gets prepared certificate.

@return the prepared certificate
consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/payload/RoundChangePayload.java