title: Can't add two merge regions in POI?
body: <p>I'm trying to add two merge regions in one row like this:</p>
  
  <pre><code>// Cell Range Address
  CellRangeAddress cellRangeAddress_1 = new CellRangeAddress(0, 0, 3, 6);
  CellRangeAddress cellRangeAddress_2 = new CellRangeAddress(0, 0, 7,9);
  
  // Creating cells
  cell = row.createCell(3); // 1
  cell.setCellStyle(headingStyle);
  cell.setCellValue("CoLUMN 1");
  
  cell = row.createCell(4); // 2
  cell.setCellStyle(headingStyle);
  cell.setCellValue("COLUMN 2");
  </code></pre>
  
  <p>The first column is merged and "COLUMN 1" is displayed. The second column is merged but the text is NOT displayed !</p>
  
  <p>Am I doing it wrong or is this a bug? I'm using Apache POI 3.7. </p>