@Override
    public void update(ComplexEventChunk<StateEvent> updatingEventChunk, Object storeEvents,
                       InMemoryCompiledUpdateSet compiledUpdateSet) {
        if (((Collection<StreamEvent>) storeEvents).size() > 0) {
            updatingEventChunk.reset();
            while (updatingEventChunk.hasNext()) {
                StateEvent updatingEvent = updatingEventChunk.next();
                try {
                    for (StreamEvent storeEvent : ((Collection<StreamEvent>) storeEvents)) {
                        updatingEvent.setEvent(storeEventPosition, storeEvent);
                        if ((Boolean) expressionExecutor.execute(updatingEvent)) {
                            for (Map.Entry<Integer, ExpressionExecutor> entry :
                                    compiledUpdateSet.getExpressionExecutorMap().entrySet()) {
                                storeEvent.setOutputData(entry.getValue().execute(updatingEvent), entry.getKey());
                            }
                        }
                    }
                } finally {
                    updatingEvent.setEvent(storeEventPosition, null);
                }
            }
        }
    }
Operator which is related to non-indexed In-memory table operations.
modules/siddhi-core/src/main/java/io/siddhi/core/util/collection/operator/CollectionOperator.java