Improve Java doc for LeaderEpochFileCache.endOffsetFor()
Author: Ben Stopford
Reviewers: Jun Rao
Closes from benstopford/KAFKA-5542
@@ -86,6 +86,10 @@ class LeaderEpochFileCache(topicPartition: TopicPartition, leo: () => LogOffsetM
* This is defined as the start offset of the first Leader Epoch larger than the
* Leader Epoch requested, or else the Log End Offset if the latest epoch was requested.
*
+ * During the upgrade phase, where there are existing messages may not have a leader epoch,
+ * if requestedEpoch is < the first epoch cached, UNSUPPORTED_EPOCH_OFFSET will be returned
+ * so that the follower falls back to High Water Mark.
+ *
* @param requestedEpoch
* @return offset
*/
