default void upgrade(
            AsyncConnectionEndpoint endpoint,
            Object attachment,
            HttpContext context,
            FutureCallback<AsyncConnectionEndpoint> callback) {
        upgrade(endpoint, attachment, context);
        if (callback != null) {
            callback.completed(endpoint);
        }
    }
Upgrades transport security of the given endpoint by using the TLS security protocol.

@param endpoint      the managed endpoint.
@param attachment the attachment the upgrade attachment object.
@param context the actual HTTP context.
@param callback result callback.

@since 5.2
httpclient5/src/main/java/org/apache/hc/client5/http/nio/AsyncClientConnectionManager.java