title: Java Apache POI: setting default column style doesnt work for existing values
body: <p>I have the following example code:</p>
  
  <pre><code>    SXSSFWorkbook wb = new SXSSFWorkbook();
      SXSSFSheet sheet = wb.createSheet("sheet");
      SXSSFRow row = sheet.createRow(0);
      SXSSFCell cell = row.createCell(0);
      cell.setCellValue("value");
  
      XSSFCellStyle cellStyle = (XSSFCellStyle) wb.createCellStyle();
      DataFormat fmt = wb.createDataFormat();
      cellStyle.setDataFormat(fmt.getFormat("@"));
      sheet.setDefaultColumnStyle(0, cellStyle);
  
      FileOutputStream out;
      try {
          out = new FileOutputStream("filename.xlsx");
          try {
              wb.write(out);
              out.close();
  
          } catch (IOException e) {
              e.printStackTrace();
          }
      } catch (FileNotFoundException e) {
          e.printStackTrace();
      }   
  </code></pre>
  
  <p>It successfully creates an excel file and puts the value "value" in it (column A, row 1). 
  I want to set the column style for column A to "@" (=Text) which is working very well but not for the cell with the already existing value "value". All other empty cells in column A are set to the style "@" successfully. 
  I have to work with SXSSFWorkbook since I am creating huge excel files.</p>