_sheetIndexesByName = new IdentityHashMap<String, Integer>();
_collaboratingWorkbookEnvironment = CollaboratingWorkbooksEnvironment.EMPTY;
_workbookIx = 0;
_stabilityClassifier = stabilityClassifier;
AggregatingUDFFinder defaultToolkit = // workbook can be null in unit tests
workbook == null ? null : (AggregatingUDFFinder)workbook.getUDFFinder();
if(defaultToolkit != null && udfFinder != null) {
defaultToolkit.add(udfFinder);
}
_udfFinder = defaultToolkit;
}