title: Creating the border for the merged cells in POI
body: <p>Could anyone explain me how to create the borders for the merged cells using Apache POI?<br>
  The Code I'm using is only affecting one cell.</p>
  
  <pre><code>sheet.addMergedRegion(new CellRangeAddress(1, 1, 2, 3));
  Cell monthCell = subheaderRow.createCell(2);
  monthCell.setCellValue(2);
  monthCell.setCellStyle(styles.get("month"));
  
  
  
  style = wb.createCellStyle();
  
  style.setBorderBottom(CellStyle.BORDER_THIN);
  style.setBorderTop(CellStyle.BORDER_THIN);
  style.setBorderLeft(CellStyle.BORDER_THIN);
  style.setBorderRight(CellStyle.BORDER_THIN);
  style.setAlignment(CellStyle.ALIGN_CENTER);
  style.setAlignment(CellStyle.ALIGN_CENTER);
  style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
  // style.setFillForegroundColor(IndexedColors.DARK_BLUE.getIndex());
  // style.setFillPattern(CellStyle.SOLID_FOREGROUND);
  // style.setFont(monthFont);
  styles.put("month", style);
  </code></pre>