String getColumnWidth(int columnIndex) {
        String width = null;
        if (columns.size() > columnIndex) {
            // Look for the width by Column.
            width = columnWidths.get(columns.get(columnIndex));
        }
        if (width == null) {
            // Look for the width by index.
            width = columnWidthsByIndex.get(columnIndex);
        }
        return width;
    }
Get the column width. Associating a width with a {@link Column} takes
precedence over setting the width of a column index.

@param columnIndex the column index
@return the column width, or null if none specified
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractCellTable.java