Expected behavior for "directory to new directory" depends on trailing slash

In Copying files and directories, 1f case "directory to new directory", it is stated that the trailing slashes in both source and target are optional. However, if source/subdir and target/newdir/ are being used, the resulting target structure is the following:

📁 target
 └── 📁 newdir
     └── 📁 subdir
          ├── 📄 subfile1
          ├── 📄 subfile2
          └── 📁 nesteddir
              └── 📄 nestedfile

Basically the subdir folder itself is taken too, not only its content.
This can be reproduced e.g. out of the box with LocalFileSystem() and the copy() method.

Is such output expected?

Start with the "Copying files and directories" section linked in the issue and reproduce the case using LocalFileSystem() and copy() with and without trailing slashes. Compare the documented expectation with the resulting target structure, then establish whether the behavior or the specification needs to change and update the relevant tests or documentation accordingly.