Change of employer - new WP - what documents?

I am currently on WP. If I change my employer (in country WP transfer), I understand that my new employer need to apply for a new WP.

But is there any document that needs to be supplied by my previous employer?

The reason for this question is that when leaving, past employer may not co-operate with relevant documents required for WP transfer.

Thanks in advance for help.

I was in same boat last year. There was no requiremnt for my old company to provide any documents to process my new workpermit.