Use case or problem
my folder like
$ tree .
.
├── assets/
├── posts/
I have published post from posts to web, assets
folder will stay in webroot like
example.org/assets/
even though I use "attachmentFolderPath": "/assets",
, pasted image path always remove /
, get 
, wihch cause image access 404
Proposed solution
use value in attachmentFolderPath