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In v2, we removed the time stamp field but add a global retention time field (see KAFKA-1634 for details); brokers will then always set the commit time stamp as the receive time, but the committed offset can be retained until its commit time stamp + user specified retention time in the commit request. If the retention time is not set (-1), the broker offset retention time will be used as default.

Note that when this API is used for a "simple consumer," which is not part of a consumer group, then the generationId must be set to -1 and the memberId must be empty (not null). Additionally, if there is an active consumer group with the same groupId, then the commit will be rejected (typically with an UNKNOWN_MEMBER_ID or ILLEGAL_GENERATION error). 

Offset Commit Response

v0, v1 and v2:
OffsetCommitResponse => [TopicName [Partition ErrorCode]]]
  TopicName => string
  Partition => int32
  ErrorCode => int16

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