[bug-66213] hack clone table code to avoid failing with edge cases

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1903410 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFSheet.java

@@ -4948,8 +4948,9 @@ public class XSSFSheet extends POIXMLDocumentPart implements Sheet, OoxmlSheetEx
                             int c = clonedTable.getStartCellReference().getCol() + i;
                             sheet.getWorkbook().setCellFormulaValidation(false);
                             for (int r = rFirst; r <= rLast; r++) {
-                                XSSFRow row = sheet.getRow(r); if (row == null) row = sheet.createRow(r);
-                                XSSFCell cell = row.getCell(c); if (cell == null) cell = row.createCell(c);
+                                XSSFRow row = sheet.getRow(r);
+                                if (row == null) row = sheet.createRow(r);
+                                XSSFCell cell = row.getCell(c, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK);
                                 cell.setCellFormula(clonedFormula);
                             }
                         }