Created attachment 35546 [details]
Corrupted file generated by JUnit test attached

Fix introduced for bug 53611 is causing another bug which produce a corrupted Excel file.

POI will generate corrupted file if dimension end column will be the last possible column (number 16384 /column XFD/).

Dimension calculation algorithm introduced in revision:
https://svn.apache.org/viewvc?view=revision&revision=1767096
has a bug, which sets dimention end cell value too big (+1 column).

This bug will lead to corrupted file when last cell will be in use.

Following test:
https://svn.apache.org/viewvc/poi/trunk/src/ooxml/testcases/org/apache/poi/xssf/usermodel/TestXSSFBugs.java?r1=1767096&r2=1767095&pathrev=1767096
has wrong assertion. Cell number 7 is H (not I) column.

Test code to easy reproduce this bug (corrupted Excel file):

@Test
public void test53611_bug() throws IOException {
    Workbook wb = new XSSFWorkbook();
    Sheet sheet = wb.createSheet("test");
    Row row = sheet.createRow(1);
    Cell cell = row.createCell(1);
    cell.setCellValue("blabla");

    row = sheet.createRow(4);
	// Allowable column range for EXCEL2007 is (0..16383) or ('A'..'XDF')
    cell = row.createCell(16383);
    cell.setCellValue("blabla");

    // we currently only populate the dimension during writing out
    // to avoid having to iterate all rows/cells in each add/remove of a row or cell
    //OutputStream str = new FileOutputStream("/tmp/53611_bug.xlsx");
    OutputStream str = new ByteArrayOutputStream();
    try {
        wb.write(str);
    } finally {
        str.close();
    }

	// Expected :B2:XFD5
	// Actual   :B2:XFE5   <-- which is out of Excel range. This will produce corrupted Excel file
    assertEquals("B2:XFD5", ((XSSFSheet)sheet).getCTWorksheet().getDimension().getRef());

    wb.close();
}

Corrupted file generated by this test also attached.