NullReferenceException when Update plugin with postimage is triggered via UpdateMultipleRequest

[ShpendG]

Describe the bug
NullReferenceException in AddPostImageAttributesToEntity when Update is triggered via UpdateMultipleRequest

To Reproduce
Steps to reproduce the behavior:

1. Create a plugin registration with a post image which triggers on update
2. Trigger an update on that entity via UpdateMultipleRequest
3. The plugin trigger throws a NullReferenceException in AddPostImageAttributesToEntity

Expected behavior
UpdateMultipleRequest should provide post images to PostOperation plugins the same way UpdateRequest does, or handle null gracefully when no post image is available