public OnDemandQuery select(Selector selector) {

        this.selector = selector;
        return this;
    }
Builder method to set a selector to the on-demand query

@param selector selector for the on-demand query
@return updated on-demand query
modules/siddhi-query-api/src/main/java/io/siddhi/query/api/execution/query/OnDemandQuery.java