Fixes for processing return array types and multi-dimensional array types in AstubxGenerator

[msridhar]

Apply special logic for parameter types to return types also, and add fixes for multi-dimensional arrays. Most of the changes are in tests.

Summary by CodeRabbit

• Bug Fixes

  • Improved nullness handling for generic type signatures, including qualified and simple nullable annotations.
  • Correctly distinguishes nullable array references from nullable array elements, including cases where both are nullable.
  • Improved handling of nullable annotations on varargs signatures.

• Tests

  • Added coverage for serialized annotations and integration diagnostics involving nullable arrays and elements.
  • Added scenarios covering nullable arrays, nullable elements, and combined nullability.

[msridhar]

This change is part of the following stack:

• Fixes for processing return array types and multi-dimensional array types in AstubxGenerator #1689 ◀

_{Change managed by git-spice.}

[coderabbitai]

Walkthrough

AstubxGenerator now handles nullable annotations across return and argument type signatures, including arrays, varargs, and qualified or simple @Nullable forms. Tests cover nullable array references, elements, multidimensional arrays, and combined annotations. Integration tests verify the corresponding NullAway diagnostics. An ignored JDK model test covers nullable arrays returned by MessageFormat.

Possibly related issues

• Issue 950: Extends JSpecify JDK model generation for nullable array return-type annotations.

Possibly related PRs

• uber/NullAway#1243: Directly relates to AstubxGenerator return-signature parsing and generator tests.
• uber/NullAway#1497: Relates to top-level nullness handling for parameter and varargs signatures.
• uber/NullAway#1641: Relates to JSpecify JDK annotation handling and nullable array tests.

Suggested reviewers: lazaroclapp, yuxincs

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main changes to return array and multidimensional array processing in AstubxGenerator.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch nullable-array-contents-from-libmodel

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In
`@jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java`:
- Around line 392-397: Update the array detection logic in AstubxGenerator to
inspect only the annotation immediately before the final [] dimension, so
inner-dimension annotations in multidimensional types are not classified as
top-level nullness. Adjust ARRAY_NULLNESS_ANNOTATION_PATTERN or its matching
logic accordingly, and add an AstubxTest regression covering String `@Nullable`
[][].

In
`@jdk-annotations/jdk-integration-test/src/test/java/com/uber/nullaway/jdkannotations/JDKIntegrationTest.java`:
- Around line 336-349: Update JDKIntegrationTest around the nullable array and
nullable element assignment checks to avoid annotating local variables with
`@Nullable`. Pass each ReturnAnnotation result directly to matching annotated
parameters, using ParameterAnnotation.takesNullableArray() for nullable array
values and takesNullableElements() for nullable-element values, while preserving
the existing incompatible-type diagnostics.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 9cac7963-c109-419c-ab4c-daf829bb71bd

📥 Commits

Reviewing files that changed from the base of the PR and between c338eba and 3964458.

📒 Files selected for processing (6)

• jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java
• jdk-annotations/astubx-generator/src/test/java/com/uber/nullaway/jdkannotations/AstubxTest.java
• jdk-annotations/jdk-integration-test/src/test/java/com/uber/nullaway/jdkannotations/JDKIntegrationTest.java
• jdk-annotations/test-annotated/src/main/java/com/uber/nullaway/jdkannotations/ReturnAnnotation.java
• jdk-annotations/test-unannotated/src/main/java/com/uber/nullaway/jdkannotations/ReturnAnnotation.java
• nullaway/src/test/java/com/uber/nullaway/JSpecifyJDKModelsTest.java

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.87%. Comparing base (a5903b1) to head (3772af0).

Files with missing lines	Patch %	Lines
.../uber/nullaway/jdkannotations/AstubxGenerator.java	92.30%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1689      +/-   ##
============================================
- Coverage     87.87%   87.87%   -0.01%     
  Complexity     3167     3167              
============================================
  Files           109      109              
  Lines         10742    10739       -3     
  Branches       2172     2171       -1     
============================================
- Hits           9440     9437       -3     
  Misses          617      617              
  Partials        685      685              

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java (1)

409-418: 📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Add Javadoc for both private helpers.

stripAnnotationsFromTypeSignature and buildTypeSignatureAnnotationPattern define the signature-key transformation. Document their behavior and the varargs case.

As per coding guidelines, “Add Javadoc for every non-trivial method, including private methods.”

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In
`@jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java`
around lines 409 - 418, Add Javadoc to both private helpers,
stripAnnotationsFromTypeSignature and buildTypeSignatureAnnotationPattern,
describing their signature-transformation behavior. Document that annotation
removal handles annotations followed by whitespace and annotations applied
directly to top-level varargs arrays before the ellipsis.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Outside diff comments:
In
`@jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java`:
- Around line 409-418: Add Javadoc to both private helpers,
stripAnnotationsFromTypeSignature and buildTypeSignatureAnnotationPattern,
describing their signature-transformation behavior. Document that annotation
removal handles annotations followed by whitespace and annotations applied
directly to top-level varargs arrays before the ellipsis.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 30c2dcc3-2ef8-4e8f-a19c-da489bd11e9f

📥 Commits

Reviewing files that changed from the base of the PR and between 947908f and 3772af0.

📒 Files selected for processing (5)

• jdk-annotations/astubx-generator/src/main/java/com/uber/nullaway/jdkannotations/AstubxGenerator.java
• jdk-annotations/astubx-generator/src/test/java/com/uber/nullaway/jdkannotations/AstubxTest.java
• jdk-annotations/jdk-integration-test/src/test/java/com/uber/nullaway/jdkannotations/JDKIntegrationTest.java
• jdk-annotations/test-annotated/src/main/java/com/uber/nullaway/jdkannotations/ReturnAnnotation.java
• jdk-annotations/test-unannotated/src/main/java/com/uber/nullaway/jdkannotations/ReturnAnnotation.java