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