docs: public static List<File> getReferenceClientBlockFileList(File blocksDir) {
          checkArgument(blocksDir.isDirectory(), "%s is not a directory", blocksDir);
          List<File> list = new LinkedList<>();
          for (int i = 0; true; i++) {
              File file = new File(blocksDir, String.format(Locale.US, "blk%05d.dat", i));
              if (!file.exists())
                  break;
              list.add(file);
          }
          return list;
      }