code: private void growDataArrays() {
      currItemsAlloc_ = SamplingUtil.getAdjustedSize(k_, currItemsAlloc_ << rf_.lg());
      if (currItemsAlloc_ == k_) {
        ++currItemsAlloc_;
      }
  
      data_.ensureCapacity(currItemsAlloc_);
      weights_.ensureCapacity(currItemsAlloc_);
      if (marks_ != null) {
        marks_.ensureCapacity(currItemsAlloc_);
      }
    }
docs: Increases allocated sampling size by (adjusted) ResizeFactor and copies items from old
  sampling. Only happens when buffer is not full, so don't need to worry about blindly copying
  the array items.