docs: static String stringValue2(IntBitSet[] arr) {
          b2.setLength(0);
          int c = 0;
          loop:
          for (; ; ) {
              boolean marked = false;
              for (; ; ) {
                  IntBitSet marks = arr[c >> 8];
                  if (marks != null && marks.get(c & 255)) break;
                  c++;
                  if (c > 0xffff) break loop;
              }
              int first = c;
              for (; c <= 0xffff; ) {
                  IntBitSet marks = arr[c >> 8];
                  if (marks == null || !marks.get(c & 255)) break;
                  c++;
              }
              int last = c - 1;
              if (last == first) b2.append(stringValue(last));
              else {
                  b2.append(stringValue(first));
                  b2.append('-');
                  b2.append(stringValue(last));
              }
              if (c > 0xffff) break;
          }
          return b2.toString();
      }