* 3. Different case
   *
   * ```
   * content-type: text/html
   * content-length: 50
   * ```
   *
   * 4. Different values
   *
   * ```
   * Content-Type: text/html
   * Content-Length: 050
   * ```
   *
   * Applications that require semantically equal headers should convert them into a canonical form
   * before comparing them for equality.
   */