@Override
    protected TableRowElement getChildElement(int row) {
        return getSubRowElement(row + getPageStart(), 0);
    }
{@inheritDoc}

<p>
The row element may not be the same as the TR element at the specified
index if some row values are rendered with additional rows.
</p>

@param row the row index, relative to the page start
@return the row element, or null if it doesn't exists
@throws IndexOutOfBoundsException if the row index is outside of the
                                  current page
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractCellTable.java