) {
      for (pushPromise in promises) {
        val pushedHeaders = mutableListOf<Header>()
        pushedHeaders.add(Header(Header.TARGET_AUTHORITY, url(pushPromise.path).host))
        pushedHeaders.add(Header(Header.TARGET_METHOD, pushPromise.method))
        pushedHeaders.add(Header(Header.TARGET_PATH, pushPromise.path))
        val pushPromiseHeaders = pushPromise.headers

    /**
     * Returns true if the request contains conditions that save the server from sending a response
     * that the client has locally. When a request is enqueued with its own conditions, the built-in
     * response cache won't be used.
     */
    private fun hasConditions(request: Request): Boolean =
      request.header("If-Modified-Since") != null || request.header("If-None-Match") != null
  }

  companion object {

 * [DNS over HTTPS implementation][doh_spec].
 *
 * > A DNS API client encodes a single DNS query into an HTTP request
 * > using either the HTTP GET or POST method and the other requirements
 * > of this section.  The DNS API server defines the URI used by the
 * > request through the use of a URI Template.
 *
 * [doh_spec]: https://tools.ietf.org/html/draft-ietf-doh-dns-over-https-13
 */
class DnsOverHttps internal constructor(