private static TraceNode extractTraceNode(Query query) {
        if (log.isLoggable(Level.FINE)) {
            QueryContext queryContext = query.getContext(false);
            if (queryContext != null) {
                Execution.Trace trace = queryContext.getTrace();
                if (trace != null) {
                    return trace.traceNode();
                }
            }
        }
        return null;
    }
If present, responses from this will set the HTTP response header with this key to the host name of this
container-search/src/main/java/com/yahoo/search/handler/SearchHandler.java