The documentation at
https://docs.mongodb.com/kafka-connector/master/kafka-sink-properties/#fieldpathnamespacemapper-settings
instructs to set "namespace.mapper" as "com.mongodb.kafka.connect.sink.topic.mapping.FieldPathNamespaceMapper" .
It should be "com.mongodb.kafka.connect.sink.namespace.mapping.FieldPathNamespaceMapper"

Acceptance Criteria

As a user, I see the correct value set for namespace.mapper.