[HUDI-736] Simplify ReflectionUtils#getTopLevelClassesInClasspath

[LeonxLJX]

Describe the issue this Pull Request addresses

[HUDI-736] ReflectionUtils#getTopLevelClassesInClasspath is written as a verbose imperative loop and contains a latent bug: if ClassLoader#getResources throws an IOException, resources stays null and the subsequent Objects.requireNonNull(resources) throws an NPE instead of degrading gracefully.

Summary and Changelog

• Rewrite the method as a stream pipeline over the package resources (Collections.list + map/filter/flatMap).
• Return an empty stream on IOException instead of crashing with an NPE.
• Extract a small private helper toDirectory to map a resource URL to a File, logging and skipping malformed URLs as before.

Impact

Minor refactor of a utility method used during classpath scanning. Behavior is unchanged for the normal path.

Risk Level

Low - utility method refactor, no behavioral change to public APIs.

Documentation Update

No documentation changes needed.

Contributor's checklist

• Read through the contributing guide
• Commit message references the issue
• Tests added for new functionality
• Documentation updated where applicable

[utafrali]

The refactor is a clear improvement: it removes the NPE footgun caused by the null-initialized resources variable and the resulting Objects.requireNonNull crash on IOException. The stream pipeline is more readable. Two issues remain: toDirectory should also catch IllegalArgumentException from new File(URI) (triggered by jar: scheme URLs in all 14 bundle Main callers), and the new IOException recovery path has no test.

[voonhous]

Please make sure that you follow the PR-description and title template, else CI will fail. Please refer to: https://hudi.apache.org/contribute/how-to-contribute/#opening-pull-requests

Please also mention in the PR body that this closes: #14554

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 78.01%. Comparing base (7b377a5) to head (ee98fce).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
...a/org/apache/hudi/common/util/ReflectionUtils.java	88.88%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #19784      +/-   ##
============================================
- Coverage     78.15%   78.01%   -0.14%     
- Complexity    33691    34008     +317     
============================================
  Files          2540     2541       +1     
  Lines        141413   142930    +1517     
  Branches      17123    17226     +103     
============================================
+ Hits         110516   111509     +993     
- Misses        23195    23690     +495     
- Partials       7702     7731      +29     

Components	Coverage Δ
hudi-common	83.54% <ø> (-0.03%)	⬇️
hudi-client	82.35% <ø> (-0.81%)	⬇️
hudi-flink	85.66% <ø> (ø)
hudi-spark-datasource	72.62% <ø> (-0.08%)	⬇️
hudi-utilities	74.51% <ø> (-0.02%)	⬇️
hudi-cli	15.06% <ø> (ø)
hudi-hadoop	70.11% <ø> (ø)
hudi-sync	75.54% <ø> (-0.03%)	⬇️
hudi-io	81.12% <88.88%> (+1.26%)	⬆️
hudi-timeline-service	83.44% <ø> (ø)
hudi-cloud	65.81% <ø> (ø)
hudi-kafka-connect	53.20% <ø> (ø)

Flag	Coverage Δ
common-and-other-modules	51.46% <88.88%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...a/org/apache/hudi/common/util/ReflectionUtils.java	75.00% <88.88%> (+34.70%)	⬆️

... and 29 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[hudi-bot]

CI report:

• ee98fce Azure: SUCCESS

Bot commands

@hudi-bot supports the following commands:

• @hudi-bot run azure re-run the last Azure build