[hotfix] Add the final and fix typo

[1996fanrui]

What is the purpose of the change

Add the final and fix typo

Brief change log

• commit1: Add the final and fix typo
• commit2: Remove the deprecated alignmentTimeout
• commit3: Remove the deprecated method
• commit4: Use method reference instead of inline lambda

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not documented

[flinkbot]

CI report:

• 9cf12b2 Azure: SUCCESS

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