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In order to achieve this we will be adding new OffsetSpecs [1] - in particular entries for EarliestLocalSpec and LatestTieredSpec.
As part of this KIP we will change how the ListOffsets API behaves. We won't add any fields, but we will introduce a new behaviour on the broker when a timestamp with value of -5 is requested. Going forward, when provided with a timestamp of -5 a broker will return the latest tiered offset. We don't need to add -4 as it has already been added as part of previous KIPs.
[1] https://kafka.apache.org/36/javadoc/org/apache/kafka/clients/admin/OffsetSpec.html
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