anchor.diff:  The `KafkaConsumer` class contains an
   https://kafka.apache.org/20/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.html#endOffsets-java.util.Collection-[endOffsets] method
   to get the end offset of a topic partition.
  -It returns a dictionnary _(topic name, partition) -> end offset_
  +It returns a dictionary _(topic name, partition) -> end offset_
   
   [source, java]
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positive.code: == Joining offsets and computing lag
  
  Both consumer offsets and topic end offsets are given per partition.
  To compute the lag we have to do a join using topic partition as key.
  
  [source, java]
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negative.code: 
  Kafka 2.0 introduced an `AdminClient` class which contains a very useful
  https://kafka.apache.org/20/javadoc/org/apache/kafka/clients/admin/AdminClient.html#listConsumerGroupOffsets-java.lang.String-org.apache.kafka.clients.admin.ListConsumerGroupOffsetsOptions-[listConsumerGroupOffsets] method.
  This method returns for a given consumer group a dictionary _(topic name, partition) -> current offset_
  
  [source, java]
  ----
  