@Override
        public void restore(Map<String, Object> state) {
            sum = (double) state.get("Sum");
            count = (long) state.get("Count");
        }
The initialization method for FunctionExecutor

@param attributeExpressionExecutors are the executors of each attributes in the function
@param processingMode               query processing mode
@param outputExpectsExpiredEvents   is expired events sent as output
@param configReader                 this hold the {@link SumAttributeAggregatorExecutor} configuration reader.
@param siddhiQueryContext           Siddhi query runtime context
modules/siddhi-core/src/main/java/io/siddhi/core/query/selector/attribute/aggregator/SumAttributeAggregatorExecutor.java