@Override
    protected StateFactory<State> init(StreamDefinition outputStreamDefinition, OptionHolder optionHolder,
                                       ConfigReader sinkConfigReader, SiddhiAppContext siddhiAppContext) {
        topicOption = optionHolder.validateAndGetOption(TOPIC_KEY);
        return null;
    }
Implementation of {@link Sink} which represents in-memory transport. This implementation can send incoming objects
to in-memory transport within JVM.
modules/siddhi-core/src/main/java/io/siddhi/core/stream/output/sink/InMemorySink.java