code: public static boolean[] hexDigitToBinary(final char hexDigit) {
          switch (hexDigit) {
          case '0':
              return new boolean[] { false, false, false, false };
          case '1':
              return new boolean[] { true, false, false, false };
          case '2':
              return new boolean[] { false, true, false, false };
          case '3':
              return new boolean[] { true, true, false, false };
          case '4':
              return new boolean[] { false, false, true, false };
          case '5':
              return new boolean[] { true, false, true, false };
          case '6':
              return new boolean[] { false, true, true, false };
          case '7':
              return new boolean[] { true, true, true, false };
          case '8':
              return new boolean[] { false, false, false, true };
          case '9':
              return new boolean[] { true, false, false, true };
          case 'a':// fall through
          case 'A':
              return new boolean[] { false, true, false, true };
          case 'b':// fall through
          case 'B':
              return new boolean[] { true, true, false, true };
          case 'c':// fall through
          case 'C':
              return new boolean[] { false, false, true, true };
          case 'd':// fall through
          case 'D':
              return new boolean[] { true, false, true, true };
          case 'e':// fall through
          case 'E':
              return new boolean[] { false, true, true, true };
          case 'f':// fall through
          case 'F':
              return new boolean[] { true, true, true, true };
          default:
              throw new IllegalArgumentException("Cannot interpret '" + hexDigit + "' as a hexadecimal digit");
          }
      }
docs: <p>
  Converts a hexadecimal digit into binary (represented as boolean array) using the default
  (Lsb0) bit ordering.
  </p>
  <p>
  '1' is converted as follow: (1, 0, 0, 0)
  </p>
  
  @param hexDigit the hexadecimal digit to convert
  @return a boolean array with the binary representation of {@code hexDigit}
  @throws IllegalArgumentException if {@code hexDigit} is not a hexadecimal digit