When removing a SXSSF sheet, ensure temp files associated with it are disposed of #57666

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1676833 13f79535-47bb-0310-9956-ffa450edef68

src/ooxml/java/org/apache/poi/xssf/streaming/SXSSFWorkbook.java

@@ -709,9 +709,16 @@ public class SXSSFWorkbook implements Workbook
     @Override
     public void removeSheetAt(int index)
     {
-        XSSFSheet xSheet=_wb.getSheetAt(index);
+        // Get the sheet to be removed
+        XSSFSheet xSheet = _wb.getSheetAt(index);
+        SXSSFSheet sxSheet = getSXSSFSheet(xSheet);
+        
+        // De-register it
         _wb.removeSheetAt(index);
         deregisterSheetMapping(xSheet);
+        
+        // Clean up temporary resources
+        sxSheet.dispose();
     }
 
     /**