public void tunnelTarget(final boolean secure) {
        Asserts.check(this.connected, "No tunnel unless connected");
        Asserts.notNull(this.proxyChain, "No tunnel without proxy");
        this.tunnelled = TunnelType.TUNNELLED;
        this.secure = secure;
    }
Tracks tunnelling to the target.

@param secure    {@code true} if the route is secure,
                 {@code false} otherwise
httpclient5/src/main/java/org/apache/hc/client5/http/RouteTracker.java