See how to insert border in Excel by using the predefined options and create your custom cell border style.
Apply or remove cell borders on a worksheet - Microsoft Support
Excel: How To Add And Create Borders
java - Add borders to cells in POI generated Excel File - Stack
How to create cell border in Excel
Excel: How To Add And Create Borders
How to add borders in Excel on iPad : r/excel
Apply or remove cell borders on a worksheet - Microsoft Support
java - Add borders to cells in POI generated Excel File - Stack
java - Apache POI set cell border is not working - Stack Overflow