Spring Fix handling of "file:" paths to non-existent files on Windows

On Windows, for setAsText, if the text argument is a file: URL for a path that does not exist, Paths.get(text) is called where text is a file: URL, which doesn't work - the result is an InvalidPathException. The Windows part is important - this issue only manifests when running on Windows.

To fix this issue, also check that the resource isn't a file before calling Paths.get(). That way, resources that are files skip to the other branch.

Comment From: candrews

I've added some tests to PathEditorTests to test for this issue. However, this issue only manifests when running on Windows (the newly added tests pass with and without this fix on other platforms).