SERVER-62332 introduced a recoverable ShardingDDLCoordinator for RefineCollectionShardKey. This new coordinator will persist a state document. It is necessary to drain the new coordinators during FCV downgrade in order to ensure that an old binary won't find state documents about a DDL coordinator it doesn't support.
Once this is done, we can also enable the feature flag that guards the new RefineCollectionShardKeyCoordinator.
- related to
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SERVER-62332 RefineCollectionShardKeyCoordinator doesn't disallow migrations while it's executing
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- Closed
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