* @return The added Sheet.
*/
public Sheet addSheet(String name, int colSize, int rowSize) {
final SheetImpl sheet = new SheetImpl(this, name, colSize, rowSize);
if (_sheetMap.containsKey(name)) {
throw new ModelException("Duplicated sheet name: "+name);
}
_sheetMap.put(name, sheet);
_sheetidMap.put(sheet.getId(), sheet);
_sheets.add(sheet);