@Override
    public void setIdleTime(long idleTime) {
        this.idleTime = idleTime;
    }
The {@link ScheduledExecutorService} waits until idleTime from the timestamp of last event
and if there are no new events arrived within that period, it will inject a new timestamp.

@param idleTime the ideal time for wait until from the timestamp of last event.
modules/siddhi-core/src/main/java/io/siddhi/core/util/timestamp/TimestampGeneratorImpl.java