immutable. This is left over from OkHttp 2.x (!) when that class was mutable. We're using the
    5.x upgrade as an opportunity to remove very obsolete APIs.
 *  Fix: Recover gracefully when Android's `NativeCrypto` crashes with `"ssl == null"`. This occurs
    when OkHttp retrieves ALPN state on a closed connection.
 *  Upgrade: [Kotlin 1.6.21][kotlin_1_6_21].

    thankful to Adrian Cole who has helped us to reach this milestone.

 *  **RC4 cipher suites are no longer supported by default.** To connect to
    old, obsolete servers relying on these cipher suites, you must create a
    custom `ConnectionSpec`.

 *  **Beta WebSockets support.**. The `okhttp-ws` subproject offers a new

know which [TLS versions](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-tls-version/) and [cipher suites](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-cipher-suite/) to offer. A client that wants to maximize connectivity would include obsolete TLS versions and weak-by-design cipher suites. A strict client that wants to maximize security would be limited to only the latest TLS version and strongest cipher suites.

Specific security vs. connectivity decisions are implemented by ...

        .tlsVersions(TlsVersion.TLS_1_3, TlsVersion.TLS_1_2)
        .supportsTlsExtensions(true)
        .build()

    /**
     * A backwards-compatible fallback configuration that works on obsolete client platforms and can
     * connect to obsolete servers. When possible, prefer to upgrade your client platform or server
     * rather than using this configuration.
     */
    @JvmField
    val COMPATIBLE_TLS =
      Builder(true)