DataSetDao: Method get(IDataStockMetaData dataStock, int startIndex, int pageSize) Adds Null Elements for Logical Stock

[Sarai Eilebrecht]

When invoking method get(IDataStockMetaData dataStock, int startIndex, int pageSize) with a logcial data stock and big page size (e.g. 1000), the methods adds null elements to list. This bug seems to only occur when method is invoked with logical stocks.