properties
dir = C:\\Users
class
System.out.println("dir: " + properties.getProperty("dir")); System.out.println("URL: " + url); Path file = Paths.get(properties.getProperty("dir")).resolve(url); System.out.println("path: " + file);
Conclusion
dir: C:\Users URL: /file/Новая папка path: C:\file\Новая папка
Where is Users disappearing?