Why it’s necessary to convert

When you use MultipartFile to upload files in Spring, you often need to change the file into a byte array before you can process it asynchronously.MultipartFile is linked to the HTTP request, therefore once that request is done, the file may not be available anymore.When you turn it into a byte array, you make a safe copy of the file in memory so that it may be processed later without needing the original request context.This ensures your asynchronous processing won’t run into situations like the file suddenly disappearing or becoming unreadable.