@Override
  public String toString() {
    return new StringJoiner(", ", PreparedCertificate.class.getSimpleName() + "[", "]")
        .add("proposalPayload=" + proposalPayload)
        .add("preparePayloads=" + preparePayloads)
        .toString();
  }
Gets prepare payloads.

@return the prepare payloads
consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/payload/PreparedCertificate.java