}
public T filter(String columnId, ColumnFilter... filters) {
DataSetOp op = getCurrentOp();
if (op == null || !(op instanceof DataSetFilter)) {
dataSetLookup.addOperation(new DataSetFilter());
}
DataSetFilter fOp = (DataSetFilter) getCurrentOp();
for (ColumnFilter filter : filters) {
if (columnId != null) filter.setColumnId(columnId);
fOp.addFilterColumn(filter);
}
return (T) this;
}