final List<Header> defheaders = new ArrayList<Header>();
defheaders.add(new BasicHeader("custom", "more stuff"));
final HttpContext context = new BasicHttpContext();
final HttpRequestInterceptor interceptor = new RequestDefaultHeaders(defheaders);
interceptor.process(request, context);
final Header[] headers = request.getHeaders("custom");
Assert.assertNotNull(headers);
Assert.assertEquals(2, headers.length);
Assert.assertEquals("stuff", headers[0].getValue());
Assert.assertEquals("more stuff", headers[1].getValue());