headers.put(HttpHeaders.ACCEPT, "application/vnd.abiquo.racks+xml;version=2.1-SNAPSHOT");
HttpRequest request = HttpRequest.builder().method("GET").endpoint(URI.create("http://foo")).headers(headers)
.payload(payload).build();
AppendApiVersionToMediaType filter = new AppendApiVersionToMediaType(new AppendApiVersionToAbiquoMimeType(
AbiquoApi.API_VERSION));
HttpRequest filtered = filter.filter(request);
Collection<String> accept = filtered.getHeaders().get(HttpHeaders.ACCEPT);