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enableStaticMembership will change the consumer group to static membership, along with changing registration timeout and expansion timeout. After that, all the joining members are required to set the member name field. Error will be returned if

1. the broker is on an old version

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1. . 
2. if the group is preparing rebalance/completing rebalance.
3. other potential failure cases.

Note that the client should already include member name field at this point. User could also use this API to change the timeout configs as they want, or leave it blank for the first time when they start to try the new membership protocolto use default value.

enableDynamicMembership will in the contrary just change the membership back to dynamic mode. Error will be returned if

1. the broker is on an old version

...

1. . 
2. if the group is preparing rebalance/completing rebalance.
3. group is already on dynamic membership

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1. .
2. other potential failure cases.

forceStaticRebalance will trigger one rebalance immediately on static membership. Error will be returned if the if 

1. the broker is on an old version

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1. .
2. if the group is preparing rebalance/completing rebalance.
3. group is on dynamic membership

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1. .
2. other potential failure cases. This is mainly used for fast scale up/down cases.

Compatibility, Deprecation, and Migration Plan

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