* requests on the same socket, and server-push. HTTP/1.1 semantics are layered on HTTP/2.
   *
   * HTTP/2 requires deployments of HTTP/2 that use TLS 1.2 support
   * [CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256], present in Java 8+ and Android 5+.
   * Servers that enforce this may send an exception message including the string
   * `INADEQUATE_SECURITY`.
   */
  HTTP_2("h2"),

  /**

      Content-Length: 3
      $prefix-Received-Millis: ${System.currentTimeMillis()}
      $prefix-Sent-Millis: ${System.currentTimeMillis()}
      Cache-Control: max-age=60

      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
      1