Release v19.62.2

Added

• Observers report when their position moves past a live event with no evidence that it was delivered: the chronicle-observer-events-suspected-skipped counter and a rate-limited warning log name the observer, partition, sequence number and reason. Failed queue dispatches to an observer are counted by chronicle-appended-events-queue-events-possibly-undelivered. Delivery behaviour is unchanged; the troubleshooting guide explains how to investigate and recover a suspected skip (#4820)