* given checked exception type. This reduces boilerplate for a common use of {@code Future} in
   * which it is unnecessary to programmatically distinguish between exception types or to extract
   * other information from the exception instance.
   *
   * <p>Exceptions from {@code Future.get} are treated as follows:
   *
   * <ul>

    enforce strict null checks.

 *  New: The response message is now non-null. This is the "Not Found" in the
    status line "HTTP 404 Not Found". If you are building responses
    programmatically (with `new Response.Builder()`) you must now always supply
    a message. An empty string `""` is permitted. This value was never null on
    responses returned by OkHttp itself, and it was an old mistake to permit