public void trace(boolean includeQuery, int traceLevel, Object... messages) {
        if ( ! isTraceable(traceLevel)) return;

        StringBuilder concatenated = new StringBuilder();
        for (Object message : messages)
            concatenated.append(message);
        trace(concatenated.toString(), includeQuery, traceLevel);
    }
Adds a trace message to this query
if the trace level of the query is sufficiently high.

@param includeQuery true to append the query root stringValue at the end of the message
@param traceLevel   the context level of the message, this method will do nothing
                    if the traceLevel of the query is lower than this value
@param messages     the messages whose toStrings will be concatenated into the trace message.
                    Concatenation will only happen if the trace level is sufficiently high.
container-search/src/main/java/com/yahoo/search/query/Trace.java