docs: public static boolean equal(File file1, File file2) throws IOException {
      checkNotNull(file1);
      checkNotNull(file2);
      if (file1 == file2 || file1.equals(file2)) {
        return true;
      }
  
      /*
       * Some operating systems may return zero as the length for files denoting system-dependent
       * entities such as devices or pipes, in which case we must fall back on comparing the bytes
       * directly.
       */
      long len1 = file1.length();
      long len2 = file2.length();
      if (len1 != 0 && len2 != 0 && len1 != len2) {
        return false;
      }
      return asByteSource(file1).contentEquals(asByteSource(file2));
    }