function.setName("out");
function.setFormula("=output // this formula does not even parse!");
SubReport subReport = new SubReport();
subReport.addExportParameter("out", "out");
subReport.addExpression(function);
MasterReport report = new MasterReport();
report.setDataFactory(new TableDataFactory(report.getQuery(), new DefaultTableModel(2,2)));
final RelationalGroup rootGroup = (RelationalGroup) report.getRootGroup();
rootGroup.getHeader().addSubReport((SubReport) subReport.derive());