public void setOrderByEventComparator(OrderByEventComparator orderByEventComparator) {
        isOrderBy = true;
        this.orderByEventComparator = orderByEventComparator;
    }
Processor implementation representing selector portion of the Siddhi query.
modules/siddhi-core/src/main/java/io/siddhi/core/query/selector/QuerySelector.java