@Override
    protected void processEventChunk(ComplexEventChunk<StreamEvent> streamEventChunk, Processor nextProcessor,
                                     StreamEventCloner streamEventCloner, ComplexEventPopulater complexEventPopulater,
                                     S state) {
        streamEventChunk.reset();
        while (streamEventChunk.hasNext()) {
            StreamEvent streamEvent = streamEventChunk.next();
            streamEvent.setBeforeWindowData(null);
        }
        streamEventChunk.reset();
        process(streamEventChunk, nextProcessor, streamEventCloner, state);
    }
The init method of the WindowProcessor, this method will be called before other methods

@param attributeExpressionExecutors the executors of each function parameters
@param configReader                 the config reader of window
@param siddhiQueryContext           the context of the siddhi query
modules/siddhi-core/src/main/java/io/siddhi/core/query/processor/stream/window/SlidingWindowProcessor.java