code: public static final BufferedInputStream buffer(InputStream is)
      {
          if (is instanceof BufferedInputStream)
          {
              return (BufferedInputStream) is;
          }
          else
          {
              return new BufferedInputStream(is);
          }
      }
docs: Wraps InputStream with BufferedInputStream if is is not BufferedInputStream.
  If it is returns is.
  @param is
  @return