XSubTotalCalculatable xSTC = (XSubTotalCalculatable)
UnoRuntime.queryInterface(XSubTotalCalculatable.class, oSheet);
SubTotalColumn[] columns = new SubTotalColumn[1];
SubTotalColumn column = new SubTotalColumn();
column.Column = 3;
column.Function = GeneralFunction.SUM;
columns[0] = column;
XSubTotalDescriptor desc = xSTC.createSubTotalDescriptor(true);