true if uri is well-formed; otherwise, false.
The UriParser.IsWellFormedOriginalString(Uri) method will return false if:
The string is not correctly escaped per RFC 2396.
The string represents an absolute URI that references an implicit file URI.
The string represents an absolute URI that is missing a forward slash before the path component.
The string contains unescaped backslashes, even if they will be treated as forward slashes.