@SuppressWarnings("unchecked")
    @Nullable
    V[][] array = (@Nullable V[][]) new Object[rowSpace.size()][columnSpace.size()];
    this.values = array;
    this.rowKeyToIndex = Maps.indexMap(rowSpace);
    this.columnKeyToIndex = Maps.indexMap(columnSpace);
    rowCounts = new int[rowKeyToIndex.size()];
    columnCounts = new int[columnKeyToIndex.size()];
    int[] cellRowIndices = new int[cellList.size()];