Remove grid lines completely from excel jasperreports

Jasperreports version - 4.5.0
Apache poi version - 3.7

Jasperreports uses apache poi for xls report generation but for xlsx report generation it uses its own ooxml implementation so you have to modify both of these libraries to remove excel grid lines completely.

For XLS - Line 744, File location - poi-3.7-src/src/java/org/apache/poi/hssf/usermodel/HSSFWorkbook.java
   HSSFSheet sheet = new HSSFSheet(this);
+ sheet.setDisplayGridlines(false);


For XLSX - Line 97, File location - jasperreports-4.5.0/src/net/sf/jasperreports/engine/export/ooxml/XlsxSheetHelper.java
- write("<sheetPr><outlinePr summaryBelow=\"0\"/></sheetPr><dimension ref=\"A1\"/><sheetViews><sheetView workbookViewId=\"0\"");
+ write("<sheetPr><outlinePr summaryBelow=\"0\"/></sheetPr><dimension ref=\"A1\"/><sheetViews><sheetView workbookViewId=\"0\" showGridLines=\"false\"");