private void peerIsCommitted(final Commit msg) {
    final boolean wasCommitted = roundState.isCommitted();
    roundState.addCommitMessage(msg);
    if (wasCommitted != roundState.isCommitted()) {
      importBlockToChain();
    }
  }
Construct prepared certificate.

@return the optional PreparedCertificate
consensus/qbft-core/src/main/java/org/hyperledger/besu/consensus/qbft/core/statemachine/QbftRound.java