The file that you want to rename represented by the FileHeader
The new file path
The current file Etag, used for concurrency checks (null will skip the check)
If the requested file does not exist in the file system, the FileNotFoundException will be thrown by the SaveChangesAsync.
Rename and move
Rename and move is basically the same operation. Directories in RavenFS are a virtual concept, which relies on the file paths. So if you want to move a file into a different "directory", simply rename it.