code: public static String sha3(String hexInput) {
          byte[] bytes = Numeric.hexStringToByteArray(hexInput);
          byte[] result = sha3(bytes);
          return Numeric.toHexString(result);
      }
docs: Keccak-256 hash function.
  
  @param hexInput hex encoded input data with optional 0x prefix
  @return hash value as hex encoded string