Fix incorrect Javadoc in DeclarativeConfigProperties

[thswlsqls]

Summary

• getScalarList(name, scalarType, defaultValue) summary claimed non-string entries are converted to a string, but they are removed (along with empty values) when they do not map to scalarType.
• getStructured(name, defaultValue) summary said "list of" but the method returns a single mapping.
• Both now match their non-default siblings (getScalarList(name, scalarType), getStructured(name)); filtering happens in YamlDeclarativeConfigProperties#getScalarList via .filter(Objects::nonNull) (sdk-extensions/declarative-config).

Testing done

• Javadoc-only change; no behavior change, no new tests.
• ./gradlew :api:incubator:check passed.
• No signature change → no apidiff. Not user-facing → no CHANGELOG entry.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: thswlsqls / name: Eunbin Son (e0e97d9)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.77%. Comparing base (824334c) to head (e0e97d9).

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #8484   +/-   ##
=========================================
  Coverage     78.77%   78.77%           
  Complexity     8579     8579           
=========================================
  Files          1009     1009           
  Lines         28993    28993           
  Branches       3599     3599           
=========================================
  Hits          22839    22839           
  Misses         5311     5311           
  Partials        843      843           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[thswlsqls]

/easycla

[jack-berg]

Thanks!

FYI - I noticed you've opened a lot of PRs and issues. Just scanning over a few, they seem like good PRs: small in scope and useful. Still, it will take some time to get through them.

In the future, try to limit the number of open PRs you have open at any one time. Drive those to completion, then open another batch. 🙂

[otelbot]

Thank you for your contribution @thswlsqls! 🎉 We would like to hear from you about your experience contributing to OpenTelemetry by taking a few minutes to fill out this survey.