public Collection<StreamEvent> findEvents(StateEvent matchingEvent, IndexedEventHolder indexedEventHolder) {
        Collection<StreamEvent> leftStreamEvents = leftCollectionExecutor.findEvents(matchingEvent, indexedEventHolder);
        if (leftStreamEvents == null) {
            return null;
        } else {
            Collection<StreamEvent> rightStreamEvents = rightCollectionExecutor.findEvents(matchingEvent,
                    indexedEventHolder);
            if (rightStreamEvents == null) {
                return null;
            } else {
                HashSet<StreamEvent> resultSet = new HashSet<StreamEvent>(leftStreamEvents);
                resultSet.addAll(rightStreamEvents);
                return resultSet;
            }
        }
    }
Implementation of {@link CollectionExecutor} which handles or condition
modules/siddhi-core/src/main/java/io/siddhi/core/util/collection/executor/OrCollectionExecutor.java