code: public double[] getRow(int row) {
          checkIndices(row, 0);
          AtomicVector rowEntry = getRow(row, -1, false);
          return (rowEntry == null)
              ? new double[cols.get()]
              : toArray(rowEntry, cols.get());
      }
docs: {@inheritDoc} The length of the returned row reflects the size of matrix
  at the time of the call, which may be different from earlier calls to
  {@link #columns()}.