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This KIP is aimed to extend the current `KStream#process` API to return output values that could be chained across the topology, as well as introducing a new `KStream#processValues` KStream#processValues  to use processor while validating keys haven't change and repartition is not required.

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 12:08:19.125 [new-process-c2e58cba-3c47-41a9-b221-adea4cd38c87-StreamThread-1] ERROR org.apache.kafka.streams.processor.internals.TaskManager - stream-thread [new-process-c2e58cba-3c47-41a9-b221-adea4cd38c87-StreamThread-1] Failed to process stream task 0_0 due to the following error: 
org.apache.kafka.streams.errors.StreamsException: Exception caught in process. taskId=0_0, processor=KSTREAM-SOURCE-0000000000, topic=words, partition=0, offset=0, stacktrace=java.lang.IllegalArgumentException: Key has changed while processing the record and requires enforcing repartitioning.

NOTE: The key validation can be defined when processing the message. Though, with punctuations it won't be possible to define the key for validation before forwarding, therefore it won't be possible to forward from punctuation. This is similar behavior to how ValueTransformers behave at the moment.

Compatibility, Deprecation, and Migration Plan

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