@Override
    public int hashCode() {

        int result = operator.hashCode();
        result = 31 * result + (durations != null ? durations.hashCode() : 0);
        return result;
    }
Time Period API. This defines all the time durations supported in Incremental Aggregation,
and the relevant operators
modules/siddhi-query-api/src/main/java/io/siddhi/query/api/aggregation/TimePeriod.java