Add @Generated annotation to Java code generated from the compiler

[kasecato]

Use case

As a NullAway user using Apollo Kotlin from Java, I want @Generated annotation added to the code generated by apollo-compiler. So that enables the NullAway option, which omits null checking of the generated Java code.

• NullAway, https://github.com/uber/NullAway
• @Generated
  • https://docs.oracle.com/en/java/javase/21/docs/api/java.compiler/javax/annotation/processing/Generated.html
  • https://docs.oracle.com/javase/8/docs/api/javax/annotation/Generated.html
• -XepDisableWarningsInGeneratedCode: Disables warnings in classes annotated with @Generated
  • https://errorprone.info/docs/flags

Describe the solution you'd like

We can add @Generated to class around JavaCodegen.kt

[BoD]

Thanks for the feature request!

I didn't know about @Generated and it sounds reasonable to apply it, but I'm concerned that javax.annotation.Generated requires a specific dependency, whereas javax.annotation.processing.Generated is in the JDK starting from version 9 while Apollo Kotlin has a minimal version of 8.

Could you maybe use ErrorProne's -XepExcludedPaths flag instead?

[kasecato]

I have two suggestions, but no strong opinions and let me close this request

1. Use jakarta.annotation.Generated at compileOnly
   • https://github.com/jakartaee/common-annotations-api/blob/3.0.0-BRANCH/api/src/main/java/jakarta/annotation/Generated.java
   • 25KB library increase is not good even if it's compileOnly
2. Create a custom @Generated in apollo-annotations
   • Overkill

[github-actions]

Do you have any feedback for the maintainers? Please tell us by taking a one-minute survey. Your responses will help us understand Apollo Kotlin usage and allow us to serve you better.