@Override public final void connect() throws IOException {
    initHttpEngine();
    boolean success;
    do {
      success = execute(false);
    } while (!success);
  }
The most recently received TLS handshake. This will be null if we haven't
connected yet, or if the most recent connection was HTTP (and not HTTPS).
gateway/platforms/servlet/src/main/java/io/apiman/gateway/platforms/servlet/connectors/ok/HttpURLConnectionImpl.java