@Override
  public void writeTo(final RLPOutput rlpOutput) {
    rlpOutput.startList();
    roundIdentifier.writeTo(rlpOutput);
    rlpOutput.writeBytes(digest);
    rlpOutput.endList();
  }
Read from rlp input and return proposal payload.

@param rlpInput the rlp input
@return the proposal payload
consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/payload/ProposalPayload.java