How authenticate a rest call from behind a corporate proxy using Rest-Assured?

Question

I'm trying to call a rest service via our corporate proxy but keep getting the response:

407 Proxy Authentication Required. Forefront TMG requires authorization to fulfill the request. Access to the Web Proxy filter is denied.

Can anyone suggest anything else I can try, or an alternative to RestAssured that supports NTLM?

This is my current code:

    PreemptiveBasicAuthScheme auth = new PreemptiveBasicAuthScheme();
    auth.setUserName("my username");
    auth.setPassword("my password");

    // was getting desperate so tried adding this 
    System.setProperty("http.proxyHost", "XXXX");
    System.setProperty("http.proxyPort", "8080");
    System.setProperty("http.proxyUser", "my username");
    System.setProperty("http.proxyPassword", "my password");
    System.setProperty("https.proxyHost", "XXXX");
    System.setProperty("https.proxyPort", "8080");
    System.setProperty("https.proxyUser", "my username");
    System.setProperty("https.proxyPassword", "my password");

    Response r = RestAssured
            .given()
            // tried with and without this 
            .header("Proxy-Authorization", auth.generateAuthToken()) 
            .proxy("XXXX", 8080)
            .get(fullPath, key, key);

Answer 1

There were a couple of issues here - the first I've sorted, the second I'm still blocked on.

Setting the proxy authentication was a simple matter of setting the correct header (as has been noted in many other posts):

.header("Proxy-Authorization", auth.generateAuthToken())

What was blocking me was that I'm calling a service running on https rather than http and the proxy does not appear to be used... so back to the drawing board.