public void trace(String message, int traceLevel) {
        trace(message, false, traceLevel);
    }
Adds a context message to this query and to the info log,
if the context level of the query is sufficiently high.
The context information will be carried over to the result at creation.
The message parameter will be included <i>with</i> XML escaping.

@param message      the message to add
@param traceLevel   the context level of the message, this method will do nothing
                    if the traceLevel of the query is lower than this value
container-search/src/main/java/com/yahoo/search/query/Trace.java