The ChangeLoggingKeyValueBytesStore implements the KeyValueStore interface which extends the ReadOnlyKeyValueStore interface. The Javadoc for ReadOnlyKeyValueStore#all states the method should never return a null value.
But when deleting a record from the ChangeLoggingKeyValueBytesStore and subsequently calling the all method, a null value is returned.
https://issues.apache.org/jira/browse/KAFKA-4750 is a related issue
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