[jira] [Created] (KAFKA-16362) Fix type-unsafety in KStreamKStreamJoin caused by isLeftSide

["Greg Harris (Jira)" <ji...@apache.org>]

Greg Harris created KAFKA-16362:
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             Summary: Fix type-unsafety in KStreamKStreamJoin caused by isLeftSide
                 Key: KAFKA-16362
                 URL: https://issues.apache.org/jira/browse/KAFKA-16362
             Project: Kafka
          Issue Type: Task
          Components: streams
    Affects Versions: 3.7.0
            Reporter: Greg Harris


The implementation of KStreamKStreamJoin has several places that the compiler emits warnings for, that are later suppressed or ignored:
 * LeftOrRightValue.make returns a raw LeftOrRightValue without generic arguments, because the generic type arguments depend on the boolean input.
 * Calling LeftOrRightValue includes an unchecked cast before inserting the record into the outerJoinStore
 * emitNonJoinedOuterRecords swaps the left and right values, and performs an unchecked cast

These seem to be closely related to the isLeftSide variable, which makes the class behave differently whether it is present on the left or right side of a join.

We should figure out if these warnings can be eliminated by a refactor, perhaps into KStreamKstreamJoin.Left and KStreamKStreamJoin.Right, or with some generic arguments.



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