Like Uri.file except that a non-empty URI path ends in a slash.
If path is not empty, and it doesn't end in a directory separator,
then a slash is added to the returned URI's path.
In all other cases, the result is the same as returned by Uri.file.
Source
factory Uri.directory(String path, {bool windows}) {
windows = (windows == null) ? Uri._isWindows : windows;
return windows ? _makeWindowsFileUrl(path, true)
: _makeFileUri(path, true);
}