Fix Issue 2393

[openamiguel]

Fix for Issue #2393 (WrongOneof mishandles new style switch statement) based on PR #2371 and PR #2124.

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[openamiguel]

@googlebot I signed it!

[cushon]

Thanks for the fix! Can you also add a test?

[openamiguel]

Sure. There isn't any WrongOneofTest currently. Can I just focus on testing that this bug pattern works on new-style switch statements?

[cushon]

There isn't any WrongOneofTest currently. Can I just focus on testing that this bug pattern works on new-style switch statements?

Sorry, we have an internal test for this, but it isn't available in open source to avoid the proto dependency in the maven build. Since there isn't already an existing test, this is fine.

[openamiguel]

@cushon thanks for the approval! Are we waiting for additional review?

[cushon]

Are we waiting for additional review?

Yes, there's a separate internal review step before the PR is merged