HTTP_GONE,
        HTTP_REQ_TOO_LONG,
        HTTP_NOT_IMPLEMENTED,
        HTTP_PERM_REDIRECT,
        -> {
          // These codes can be cached unless headers forbid it.
        }

        HTTP_MOVED_TEMP,
        HTTP_TEMP_REDIRECT,
        -> {
          // These codes can only be cached with the right response headers.
          // http://tools.ietf.org/html/rfc7234#section-3