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When a worker receives a request to this endpoint, it will:

1. Check to see if a rebalance is pending and, if it is, serve an HTTP 409 CONFLICT response. (This step is actually unnecessary and has been removed from the implementation; see

   Jira
   server ASF JIRA serverId 5aa69414-a9e9-3523-82ec-879b028fb15b key KAFKA-15059

   )
2. Check to see if it is the leader. If it is not the leader, either forward the request to the leader or fail the request, using at most two hops. This two-hop strategy is already implemented in Connect for other REST endpoints that require forwarding of requests, so it is not described in great detail here.
3. Verify that the connector in the request URL both exists and is a source connector; if not, fail the request.
4. Read to the end of the config topic.
5. If there is a task count record for the connector in the config topic after the latest set of task configs for the connector, serve an empty-bodied 200 response.
6. If there is an existing task count record for the connector in the config topic, and either the task count in that record is above 1 or the new number of tasks for the connector is above 1*:
   1. Fence out all producers that may still be active for prior task instances of this connector by instantiating an admin client using the connector principal and invoking Admin::fenceProducers (a new API described below; see Admin API to Fence out Transactional Producers). The transactional IDs will be the IDs that each task of the connector would have used, assuming as many tasks were active as the most recent task count record for the connector. This will be done in parallel.
   2. If the leader receives a request to write new task configs for the connector during this period, the round of fencing will be immediately cancelled and an HTTP 409 CONFLICT response will be served.
7. Write the new task count record for the fenced-out connector to the config topic
8. Read to the end of the config topic to verify that the task count record has been written successfully.
9. Serve an empty-bodied 200 response.

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