code: public static boolean isAbsolutePath(String filename) {
          File file = new File(filename);
          boolean absolute = file.isAbsolute();
          if (absolute && OperatingSystem.isFamily(OperatingSystem.WINDOWS)) {
              if (filename.startsWith("\\\\") && !filename.matches("\\\\\\\\.*\\\\.+")) {
                  absolute = false;
              }
          }
          return absolute;
      }
docs: CopiedFromAnt