*     [RealConnection.isEligible] for details.
 *
 *  3. Attempt plans from prior connect attempts for this call. These occur as either follow-ups to
 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost
 *     a race in fast follow-up.
 *
 *  4. If there's no existing connection, make a list of routes (which may require blocking DNS

   noCache, noStore, noTransform, onlyIfCached, sMaxAgeSeconds
 * **Challenge**: authParams, charset, realm, scheme
 * **CipherSuite**: javaName
 * **ConnectionSpec**: cipherSuites, supportsTlsExtensions, tlsVersions
 * **Cookie**: domain, expiresAt, hostOnly, httpOnly, name, path, persistent, value
 * **Dispatcher**: executorService
 * **FormBody**: size

        .newBuilder()
        .hostnameVerifier(
          RecordingHostnameVerifier(),
        ) // Attempt RESTRICTED_TLS then fall back to MODERN_TLS.
        .connectionSpecs(Arrays.asList(ConnectionSpec.RESTRICTED_TLS, ConnectionSpec.MODERN_TLS))
        .sslSocketFactory(
          suppressTlsFallbackClientSocketFactory(),
          handshakeCertificates.trustManager,
        ).build()

    configure OkHttp 3.13 to allow TLSv1 and TLSv1.1 connections:

    ```
    OkHttpClient client = new OkHttpClient.Builder()
        .connectionSpecs(Arrays.asList(ConnectionSpec.COMPATIBLE_TLS))
        .build();
    ```

 *  New: You can now access HTTP trailers with `Response.trailers()`. This method may only be called
    after the entire HTTP response body has been read.