@JsonCreator
  public static Hash fromHexString(final String str) {
    return new Hash(Bytes32.fromHexStringStrict(str));
  }
Parse an hexadecimal string representing a hash value.

@param str An hexadecimal string (with or without the leading '0x') representing a valid hash
    value.
@return The parsed hash.
@throws NullPointerException if the provided string is {@code null}.
@throws IllegalArgumentException if the string is either not hexadecimal, or not the valid
    representation of a hash (not 32 bytes).
datatypes/src/main/java/org/hyperledger/besu/datatypes/Hash.java