Java base64 skrypt decrypt

import java.util.Base64;

class Base64Decode {
  public static void main(String[] args) {
    String b64 = "Z3VydQ==";
    byte[] decoder = Base64.getDecoder().decode(b64);
    String str = new String(decoder);
    System.out.println(str); //-> "guru"
  }
}
Breakable Bug