code: public static boolean isAbsolute(String path) {
          Pattern DRIVE_PATTERN = Pattern.compile("[A-Za-z]:[\\\\/].*");
          return path.startsWith("/") || DRIVE_PATTERN.matcher(path).matches();
      }
docs: See {@link hudson.FilePath#isAbsolute(String)}.
  @param path String representing <code> Platform Specific </code> (unlike FilePath, which may get Platform agnostic paths), may not be null
  @return true if String represents absolute path on this platform, false otherwise