KAFKA-7653 [WIP] Add KeySerde and ValueSerde types

[mtranter]

KAFKA-7653

https://issues.apache.org/jira/browse/KAFKA-7653

Added two new types KeySerde[T] and ValueSerde[T] and changed signatures of the relevant methods to accept KeySerde and ValueSerde instead of Serde as implicit params.

Also added KeyValueAgnostic object to org.apache.kafka.streams.scala.Serdes, to provide implicit conversions from Key/ValueSerdes to plain old Serde to help minimise impact on existing users

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

@guozhangwang @miguno @vvcephei

[vvcephei]

Hi @mtranter,

Thanks for taking this on.

I thought the idea of the new types was to pre-configure the serdes as key or value, but I didn't see this in the code... Did I miss it, or did I miss the point?

Thanks,
-John

[bbejeck]

@mtranter any updates on this PR?

[mjsax]

Closing this stale PR due to inactivity. It seems the corresponding KIP-513 (https://cwiki.apache.org/confluence/display/KAFKA/KIP-513%3A+Distinguish+between+Key+and+Value+serdes+in+scala+wrapper+library+for+kafka+streams) as abandoned, too.