Fix NPE in RadTestContextProviderKt.chooseTargetForFile

[ujohnny]

For some reason in Java/Kotlin interop a nullable type was visible as non-nullable in kotlin, so this led to unexpected NPE in code. Fixed with proper annotations on the Java side and adjusted the documentation.

[gemini-code-assist]

Summary of Changes

Hello @ujohnny, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a NullPointerException occurring in Java/Kotlin interop within the "RadTestContextProviderKt.chooseTargetForFile" function. The fix involves explicitly marking nullable return types in Java code using JetBrains annotations, which allows Kotlin to correctly infer and handle potential null values. This ensures robust null safety and prevents runtime errors when integrating Java and Kotlin components.

Highlights

• Java Nullability Annotations: Added "@NotNull" and "@nullable" annotations to "ListenableFuture" return types in "SourceToTargetFinder.java" and "FuturesUtil.java" to accurately reflect potential null results, improving Java/Kotlin interop.
• Kotlin Null Safety Handling: Updated Kotlin code in "RadTestContextProvider.kt" to correctly handle nullable "ListenableFuture" results from Java by using "orEmpty()" to provide a default empty collection, preventing NPEs.
• Coroutine Refactoring: Replaced "async { ... }.asListenableFuture()" with the more concise "future { ... }" construct in "RadTestContextProvider.kt" for creating "ListenableFuture"s from coroutines.

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[gemini-code-assist]

Code Review

This pull request effectively resolves a NullPointerException caused by a Java/Kotlin interoperability issue where a nullable type was treated as non-nullable. The fix, which involves adding proper nullability annotations in the Java code and handling the potential null value in the Kotlin code, is correct and well-implemented. The changes also improve the code by using the more direct future coroutine builder. I have one suggestion to improve the consistency of a function's return value.

[ujohnny]

/gemini review

[gemini-code-assist]

Code Review

This pull request effectively addresses a NullPointerException (NPE) issue arising from Kotlin/Java interop by introducing @NotNull annotations and providing non-null fallback values (empty lists) in FuturesUtil and related SourceToTarget helper classes. This ensures that methods returning collections consistently provide non-null results, aligning with Kotlin's null-safety principles. The changes also include minor refactoring, such as leveraging var for type inference and utilizing the kotlinx.coroutines.guava.future builder for more concise asynchronous code.

[ujohnny]

/gemini review

[gemini-code-assist]

Code Review

This pull request effectively resolves a NullPointerException in RadTestContextProvider.kt that stemmed from a Java/Kotlin interoperability issue with nullability. The fix is robust, involving the addition of @NotNull annotations to Java APIs to guarantee non-null return values, which prevents unexpected nulls in the Kotlin code. The changes are propagated consistently up the call stack, from FuturesUtil to SourceToTargetFinder and SourceToTargetHelper, and the calling Kotlin code is simplified accordingly. Overall, this is a high-quality change that improves code safety and clarity. I have one suggestion to further improve the robustness of the future handling logic.

[LeFrosch]

Is there still a reason for this change after introducing the non-nullable API?