public static Bytes zeroLeftPad(final Bytes input, final int requiredLength) {
    final int paddingByteCount = Math.max(0, requiredLength - input.size());
    return Bytes.concatenate(Bytes.wrap(new byte[paddingByteCount]), input)
        .slice(0, requiredLength);
  }
Zero left pad bytes.

@param input the input
@param requiredLength the required length
@return the bytes
consensus/common/src/main/java/org/hyperledger/besu/consensus/common/ConsensusHelpers.java