public void setNext(Processor next) {
        super.setNext(next);
        this.querySelector = (QuerySelector) ((StreamPreStateProcessor) next).getThisLastProcessor().getNextProcessor();
    }
Implementation of {StreamJunction.Receiver} to receive events to be fed into
single stream stateless queries(Filter).
modules/siddhi-core/src/main/java/io/siddhi/core/query/input/SingleProcessStreamReceiver.java