@Override
        public void restore(Map<String, Object> state) {
            sum = (Long) state.get("Sum");
            mean = (Long) state.get("Mean");
            stdDeviation = (Long) state.get("stdDeviation");
            count = (int) state.get("Count");
        }
Standard deviation abstrct aggregator for Double values
modules/siddhi-core/src/main/java/io/siddhi/core/query/selector/attribute/aggregator/StdDevAttributeAggregatorExecutor.java