code: public Stream window(WindowConfig windowConfig, Fields inputFields, Aggregator aggregator, Fields functionFields) {
          // this store is used only for storing triggered aggregated results but not tuples as storeTuplesInStore is set
          // as false int he below call.
          InMemoryWindowsStoreFactory inMemoryWindowsStoreFactory = new InMemoryWindowsStoreFactory();
          return window(windowConfig, inMemoryWindowsStoreFactory, inputFields, aggregator, functionFields, false);
      }
docs: Returns a stream of aggregated results based on the given window configuration which uses inmemory windowing tuple store.
  
  @param windowConfig window configuration like window length and slide length.
  @param inputFields input fields
  @param aggregator aggregator to run on the window of tuples to compute the result and emit to the stream.
  @param functionFields fields of values to emit with aggregation.
  
  @return the new stream with this operation.