I am having trouble locating the methods to "Check Out" (or otherwise lock) and "Check In" documents in a SharePoint Online library/list using the Graph SDK. I don't actually see the REST calls listed either, but I have to believe they are somewhere, because OneDrive for Business webclient exposes these functions.
Basically, in some version-control scenarios, SharePoint admins and/or designers can "Require Check Out" in the library's Versioning Settings configuration. Editing a document is then a multi-step process, one of the first steps is to "Check Out" the document from the library so it is locked for edits to the current user. I can not find this method (and the mirror method "Check In") in reviewing the REST docs or the Graph SDK source code on GitHub. These methods would be required if a library is configured to "Require Check Out".
I have looked through the (Graph)List and ListItem objects pretty thoroughly (including the Versions relationship/collection) and can not locate the methods. I would have expected them to be available on a ListItem object.
If anyone has any code to work with document ListItems in this manner - or simply knows where to find these methods, it would be very helpful.