Github user zentol commented on the issue:
https://github.com/apache/flink/pull/4769
The current solution also straight up doesn't work:
```
java.lang.ClassCastException: java.lang.Object cannot be cast to
org.apache.flink.metrics.MetricGroup
at
org.apache.flink.streaming.connectors.kafka.internals.AbstractFetcher.registerOffsetMetrics(AbstractFetcher.java:555)
at
org.apache.flink.streaming.connectors.kafka.internal.Kafka09Fetcher.<init>(Kafka09Fetcher.java:99)
at
org.apache.flink.streaming.connectors.kafka.internal.Kafka09FetcherTest.testCancellationWhenEmitBlocks(Kafka09FetcherTest.java:376)
```
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