Major Description
We've observed that many usage of the consumer.committed calls are made for not only one partition, but for a batch of partitions. On the other hand, the OffsetFetchRequest protocol actually allows for multiple partitions within one request.
I'd propose we add an overloaded function of KafkaConsumer that takes
Map<TopicPartition, OffsetAndMetadata> committed(Collection<TopicPartition> partitions, final Duration timeout)
And then deprecate the existing function that only takes on partition.
