Improve authoritiesClaimName validation in JwtGrantedAuthoritiesConverter

[chanbinme]

Summary

Use StringUtils.hasText() instead of null check in getAuthoritiesClaimName() to properly handle empty strings and whitespace-only strings.

Problem

The current null check (!= null) incorrectly treats empty strings ("") and whitespace-only strings (" ") as valid claim names. While setAuthoritiesClaimName() validates with Assert.hasText(), the field can be set through other means (reflection, constructors, etc.) that bypass this validation.

Changes

• Replace != null check with StringUtils.hasText()
• Add comprehensive test coverage for blank claim names

Testing

Added parameterized tests covering empty strings, whitespace strings, and null values using ReflectionTestUtils to simulate edge cases.

Impact

• Fixes edge case bugs with blank claim names
• Maintains full backward compatibility
• Follows defensive programming principles
• All existing tests pass

This is a straightforward bug fix that improves robustness without breaking changes.

[jzheaux]

Thanks for the PR, @chanbinme! I've left my feedback inline.

[chanbinme]

Hi @jzheaux,

Thank you so much for your helpful feedback!
I've incorporated your suggestions and pushed the changes.
When you have a moment, could you please take another look?
I've also left some comments on the inline feedback for further discussion.

Thanks again for your time and support!

[chanbinme]

Thanks for the PR, @chanbinme! I've left my feedback inline.

Hi @jzheaux 👋

No rush at all, just wanted to make sure this didn't get lost in notifications.
Happy to address any additional feedback when you have time.

[jzheaux]

Thanks for the updates, @chanbinme! This is now merged into main.