}

    public void test_isUrlChar_allValidChars() {
        // Test all valid URL characters in a comprehensive way
        String validChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-*_:/+%=&?#[]@~!$'(),;";
        for (char c : validChars.toCharArray()) {
            assertTrue("Character '" + c + "' should be a valid URL character", CharUtil.isUrlChar(c));
        }
    }

     */
    private Base64() {
        // Utility class - not instantiable
    }

    private static final String ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    /**
     * Base-64 encodes the supplied block of data.  Line wrapping is not
     * applied on output.
     *
     * @param bytes The block of data that is to be Base-64 encoded.

   * @since 32.0.0
   */
  public abstract BaseEncoding ignoreCase();

  private static final BaseEncoding BASE64 =
      new Base64Encoding(
          "base64()", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", '=');

  /**
   * The "base64" base encoding specified by <a
   * href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648 section 4</a>, Base 64 Encoding.