docs: public static String toHexString(final BitSet set) {
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          PrintWriter writer = new PrintWriter(out);
          final long[] longs = set.toLongArray();
          for (long aLong : longs) {
              writer.write(Long.toHexString(aLong));
          }
          writer.flush();
  
          return new String(out.toByteArray(), java.nio.charset.StandardCharsets.UTF_8);
      }