Creates a new BatchBuffer with the given parameters.

Create a new TimeWindowsKafkaService with the given Kafka reader and writer, start time in milliseconds, time window size in milliseconds and capacity.

Buffer holding batches of messages, each key is one of a discrete windowId (startMillis + n x timeWindowSizeMillis) and the value is a batch of messages received within that window.

A service which composes a new Kafka message out of the batch of messages collected within the time window.