@Override
        public boolean canDestroy() {
            return count == 0 && sum == 0.0 && mean == 0.0 && stdDeviation == 0.0;
        }
Standard deviation abstrct aggregator for Double values
modules/siddhi-core/src/main/java/io/siddhi/core/query/selector/attribute/aggregator/StdDevAttributeAggregatorExecutor.java