public void addEvent(MetaStreamEvent metaStreamEvent) {
        metaStreamEvents[streamEventCount] = metaStreamEvent;
        streamEventCount++;
    }
Class to hold mapping between StreamEvents and respective StateEvent.
This consist of array of MetaStreamEvents which represent each
StreamEvent within StateEvent
modules/siddhi-core/src/main/java/io/siddhi/core/event/state/MetaStateEvent.java