*
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

   */
  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%

   */
  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%

     *
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

    /**
     * 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;

 * <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.

    }

    /**
     * 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

   *
   * <p>Unlike {@link Integer#parseInt(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits,
   * and returns {@code null} if non-ASCII digits are present in the string.
   *
   * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even though {@link
   * Integer#parseInt(String)} accepts them.
   *

///

## About HTTP status codes { #about-http-status-codes }

/// note

If you already know what HTTP status codes are, skip to the next section.

///

In HTTP, you send a numeric status code of 3 digits as part of the response.

These status codes have a name associated to recognize them, but the important part is the number.

In short:

    }

    @Test
    void isAllDigitsHandlesEmptyString() {
        // Empty string technically has no non-digit characters, so it returns true
        assertTrue(UniAddress.isAllDigits(""), "isAllDigits should return true for empty string (no non-digits)");
    }

    /* ---------------------------------------------------------------------