[Batch Plugin] Plugin implementations should use PHP attributes instead of annotations

Thank you @elc for pointing this out. I am happy to amend to code. I looked at the links you shared - can you elaborate on how to support fallback - your second point (Add Attributes with fallback to Annotations for BC). I do want any modules using this will continue to work.

Thanks again :-)

This is where Drupal Core uses Attributes primarily with a fallback to Annotation:
https://git.drupalcode.org/project/drupal/-/blob/d7b47da6deda8a417760c26...

This is part of the commit linked the summary.

This is the constructor of the DefaultPluginManager which is given the Attribute and Annotation classes for discovery:
https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Plugin%21...