@Deprecated
    public void initializeAfterWindowData() {
        if (onAfterWindowData == null) {
            onAfterWindowData = new ArrayList<Attribute>();
        }
    }
Class to hold meta info about StreamEvent.
This is also used to update variable positions on executors
modules/siddhi-core/src/main/java/io/siddhi/core/event/stream/MetaStreamEvent.java