chore: upgrade checkstyle to 8.28

[gmshake]

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New Feature Submissions:

1. Does your submission pass tests?
2. Does mvn checkstyle:check pass ?
3. Have you added your new test classes to an existing test suite in alphabetical order?

Changes to Existing Features:

• Does this break existing behaviour? If so please explain.
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully run tests with your changes locally?