for (int i = 1; i < bytes.length; i++) {
      val |= (bytes[i] & 0xFF) << (i * 8);
    }
    return val;
  }

  /**
   * Returns a string containing each byte of {@link #asBytes}, in order, as a two-digit unsigned
   * hexadecimal number in lower case.
   *
   * <p>Note that if the output is considered to be a single hexadecimal number, whether this string

            }
          }
        }
      }
    }
  }

  @AndroidIncompatible // slow
  @GwtIncompatible // Doubles.tryParse
  public void testTryParseAllCodePoints() {
    // Exercise non-ASCII digit test cases and the like.
    char[] tmp = new char[2];
    for (int i = Character.MIN_CODE_POINT; i < Character.MAX_CODE_POINT; i++) {
      Character.toChars(i, tmp, 0);

		// like an IP address.
		isNotNumber := false
		for i := range len(piece) {
			switch {
			case (piece[i] >= 'a' && piece[i] <= 'z' ||
				piece[i] == '-'):
				// Found a non-digit character, so
				// this piece is not a number.
				isNotNumber = true
			case piece[i] >= '0' && piece[i] <= '9':
				// Nothing to do.
			default:
				// Found invalid character.
				return false
			}

as a numeric constant: <code>\x</code> followed by exactly two hexadecimal
digits; <code>\u</code> followed by exactly four hexadecimal digits;
<code>\U</code> followed by exactly eight hexadecimal digits, and a
plain backslash <code>\</code> followed by exactly three octal digits.
In each case the value of the literal is the value represented by
the digits in the corresponding base.
</p>

<p>

E se você clicar, verá um pequeno formulário de autorização para digitar um `username` e um `password` (e outros campos opcionais):

<img src="/img/tutorial/security/image02.png">

/// note | Nota

Não importa o que você digite no formulário, ainda não vai funcionar. Mas nós vamos chegar lá.

///

Claro que este não é o frontend para os usuários finais, mas é uma ótima ferramenta automática para documentar interativamente toda a sua API.

   */
  static BigInteger randomNonNegativeBigInteger(int numBits) {
    int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {
      return new BigInteger(digits, RANDOM_SOURCE).setBit(digits);
    }
  }

  /**
   * Equivalent to calling randomPositiveBigInteger(numBits) and then flipping the sign with 50%

    /**
     * Convert hexadecimal characters to binary integer
     *
     * @param arr the character array containing hex digits
     * @param offset the starting position in the array
     * @param length the number of hex digits to convert
     * @return the integer value of the hex digits
     */
    public static int hex_to_bin(final char[] arr, final int offset, final int length) {
        int value = 0;

 *
 * This matches IPv6 addresses as a hex string containing at least one colon, and possibly
 * including dots after the first colon. It matches IPv4 addresses as strings containing only
 * decimal digits and dots. This pattern matches strings like "a:.23" and "54" that are neither IP
 * addresses nor hostnames; they will be verified as IP addresses (which is a more strict
 * verification).
 */

    }

    /**
     * Checks if the given character is a valid URL character.
     *
     * Valid URL characters include:
     * - Lowercase letters (a-z)
     * - Uppercase letters (A-Z)
     * - Digits (0-9)
     * - Special characters: . - * _ : / + % = & ? # [ ] @ ~ ! $ ' ( ) , ;
     *
     * @param c the character to check
     * @return {@code true} if the character is a valid URL character, {@code false} otherwise

 * <ul>
 * <li>Mixing of '<code>-</code>' (hyphen) and '<code>.</code>' (dot) separators,</li>
 * <li>Transition between characters and digits also constitutes a separator:
 *     <code>1.0alpha1 =&gt; [1, [alpha, 1]]</code></li>
 * <li>Unlimited number of version components,</li>
 * <li>Version components in the text can be digits or strings,</li>
 * <li>Strings are checked for well-known qualifiers, and the qualifier ordering is used for version ordering.