List files in folder with Google Drive v3

I want to list all files in a Google drive Folder with Google drive api v3. I have the Folder id already so i Need to get the Folder by id and then list its files. (and get file Information further on later) The Problem is the api doc just Shows api calls for files but not for Folders. See https://developers.google.com/drive/api/v3/reference

Can't that be done in v3 anymore? v2 offers such calls if i remember correctly but i suppose i shouldn't use v2 anymore because it will be deprecated in near future, won't it?

EDIT: The Folder is public by the way