code: static public byte[] decode(String base16) {
          String string = base16.replaceAll("\\s", "");  // remove all white space
          int length = string.length();
          byte[] bytes = new byte[(int) Math.ceil(length / 2.0)];
          for (int i = 0; i < bytes.length; i++) {
              decodeByte(string, i, bytes);
          }
          return bytes;
      }
docs: This function decodes a base 16 string into its corresponding byte array.
  
  @param base16 The base 16 encoded string.
  @return The corresponding byte array.