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No special upgrade path is necessary, and this change should be transparent to the user – they will just see that cooperative rebalancing is enabled.

Rejected Alternatives

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1. Some cooperative-sticky related defects might not freed before V3.0
   → We've marked an important defect KAFKA-12896  as blocker for V3.0. Please raise any important defect if any.
2. cooperative-sticky assignor is also very new for C/C++ users in librdkafka, so not many in that community have tried incremental cooperative yet. And bugs are still recently being worked out there too.
   → Client can always change the assignor to other assignors if there are still bugs in the library.