MINOR: Cleanups in Test Common Module

[sjhajharia]

Now that Kafka Brokers support Java 17, this PR makes some changes in
test-common module. The changes mostly include:

• Collections.emptyList(), Collections.singletonList() and
  Arrays.asList() are replaced with List.of()
• Collections.emptyMap() and Collections.singletonMap() are replaced
  with Map.of()
• Collections.singleton() is replaced with Set.of()

Reviewers: Ken Huang [email protected], Chia-Ping Tsai
[email protected]

[m1a2st]

Thank @sjhajharia for this patch, left some comments

Could you update ClusterTemplate L47 JavaDoc

[sjhajharia]

Thanks @m1a2st for the review,
I have addressed the suggestions.
Requesting a re-review!

[m1a2st]

Thanks, LGTM

[chia7712]

@sjhajharia thanks for this cleanup. one small comment is left. PTAL

[sjhajharia]

Hey @chia7712 ,
I had to revert the change suggested by you. The reason is that the method is used in a different way by the test in that class. Removal led to test failures.

[chia7712]

I had to revert the change suggested by you. The reason is that the method is used in a different way by the test in that class. Removal led to test failures.

you are right, Please ignore my previous comment 😢

[sjhajharia]

No worries @chia7712
This PR is ready for review.
TIA!