MINOR: Replace Collections and Arrays factory methods with Java 9+ equivalents in tools

[sunm2n]

Replaces legacy collection factory methods in the tools module with
their Set.of() / List.of() / Map.of() equivalents, and removes imports
that become unused

Changed

• ConfigCommand — Collections.singleton() → Set.of()
• ConnectInternalTopicsTest — Collections.singleton() → Set.of()
• DumpLogSegmentsTest — Collections.singletonList() → List.of(),
  Collections.emptyMap() → Map.of(), Arrays.asList() → List.of()
• StreamsGroupCommandTest — Arrays.asList() → List.of()

Deliberately left unchanged

• ConfigCommandTest#511 and ShareGroupCommandTest#265 —
  Collections.singletonMap() with a null value; Map.of() rejects nulls
• Collections.nCopies(), disjoint(), emptyIterator() — no
  List.of()-style equivalent
• java.util.Arrays imports in the two files above — still needed for
  Arrays.stream()

Verification

• ./gradlew tools:test --tests ConfigCommandTest --tests
  DumpLogSegmentsTest --tests ConnectInternalTopicsTest --tests
  StreamsGroupCommandTest
• ./gradlew tools:checkstyleMain tools:checkstyleTest
  tools:spotlessCheck

Reviewers: Ken Huang s7133700@gmail.com

[m1a2st]

Thanks for the patch! Could you also clean up the tools test module? There are a few files there with the same pattern.

[sunm2n]

Thanks for the review! I've pushed a second commit that cleans up the tools test module

ConnectInternalTopicsTest and DumpLogSegmentsTest are updated — Collections.singleton(), singletonList() and emptyMap() are replaced with Set.of(), List.of() and Map.of(), and the now-unused java.util.Collections imports are removed

I deliberately left a few call sites alone:

• ConfigCommandTest#511 and ShareGroupCommandTest#265 use Collections.singletonMap() with a null value, and Map.of() rejects nulls
• Collections.nCopies(), disjoint() and emptyIterator() have no List.of()-style equivalent

Let me know if you'd prefer a different scope

[m1a2st]

Thanks for the update, we can also replace Arrays.asList() with List.of() in the following files:

• DumpLogSegmentsTest
• StreamsGroupCommandTest

And please update the PR title and description.

[sunm2n]

Done — Arrays.asList() is replaced with List.of() in both files, and I've updated the PR title and description to match the wider scope

One note: I kept the java.util.Arrays imports in both files, since they still use Arrays.stream()

[m1a2st]

Thanks for the patch, LGTM