We need to be able to read Excel 2007 OOXML (.xlsx) files in our application, and in order to do so, I upgraded from POI 3.0 to 3.5. However after the upgrade, I am getting this exception: java.lang.NoSuchMethodError: org.apache.poi.hssf.usermodel.HSSFDateUtil.isCellDateFormatted(Lorg/apache/poi/hssf/usermodel/HSSFCell;)Z at org.dbunit.dataset.excel.XlsTable.getValue(XlsTable.java:153) at org.dbun