docs: protected void appendCopiesUntil(PointableRoaringArray highLowContainer, short stoppingKey) {
      final int stopKey = toIntUnsigned(stoppingKey);
      MappeableContainerPointer cp = highLowContainer.getContainerPointer();
      while (cp.hasContainer()) {
        if (toIntUnsigned(cp.key()) >= stopKey) {
          break;
        }
        extendArray(1);
        this.keys[this.size] = cp.key();
        this.values[this.size] = cp.getContainer().clone();
        this.size++;
        cp.advance();
      }
    }