I have wondered this many times myself. This class was introduced in: * https://github.com/apache/kafka/pull/3770 * https://cwiki.apache.org/confluence/display/KAFKA/KIP-182%3A+Reduce+Streams+DSL+overloads+and+allow+easier+use+of+custom+storage+engines
Interestingly, it's not a lower bound (it's exact) in the KIP. I couldn't find any discussion of switching from exact to lower bound in the PR, the Jira, or the KIP. There are many other method parameters that have lower-bound generics, so it was likely something that everyone had on their mind and didn't need to talk about. Or, it was just a carryover from the other methods that `Produced` replaced, and I just didn't dig deep enough. I'm having a hard time imagining a situation in which the exact bound would be too tight. But of course my failure of imagination is not a proof. Perhaps it's just that, which we do need to have an exact bound on the serdes, a lower bound is sufficient on the partitioner. Maybe @guozhangwang @dguy @bbejeck or @mjsax can shed some light on it. Your question is still valid, but just for the sake of argument, can you let us know why the bounded type is a problem for the sugared `Produced` ? [ Full content available at: https://github.com/apache/kafka/pull/5551 ] This message was relayed via gitbox.apache.org for [email protected]
