public static HttpResponse newInstance(int status) {
        return new HttpResponse(null, status, null, null);
    }
<p>Returns the set of trailer header fields of this HttpResponse. These are typically meta-data that should have
been part of {@link #headers()}, but were not available prior to calling {@link
ResponseHandler#handleResponse(Response)}. You must NOT WRITE to these headers AFTER calling {@link
ContentChannel#close(CompletionHandler)}, and you must NOT READ from these headers BEFORE {@link
ContentChannel#close(CompletionHandler)} has been called.</p>

<p><b>NOTE:</b> These headers are NOT thread-safe. You need to explicitly synchronized on the returned object to
prevent concurrency issues such as ConcurrentModificationExceptions.</p>

@return The trailer headers of this HttpRequest.
container-core/src/main/java/com/yahoo/jdisc/http/HttpResponse.java