@Test
public void createWorkbook() throws Exception {

    final ClassLoader classLoader = getClass().getClassLoader();
    final File file = new File(classLoader.getResource("json/release-excel-export.json").getFile());
    final JsonToObject releasePackageJsonToObject = new ReleasePackageJsonToObject(file);
    final ReleasePackage releasePackage = (ReleasePackage) releasePackageJsonToObject.toObject();
    final ExcelFile releaseExcelFile = new ReleaseExportFile(new ArrayList<>(releasePackage.getReleases()));
    final Workbook workbook = releaseExcelFile.createWorkbook();
       try (FileOutputStream outputStream = new FileOutputStream("/home/mihai/ocds-export.xlsx")) {
           workbook.write(outputStream);
       }
    Assert.assertEquals("Number of sheets", 6, workbook.getNumberOfSheets());
    Assert.assertNotNull("release sheet", workbook.getSheet("release"));
    Assert.assertNotNull("tender sheet", workbook.getSheet("tender"));
    Assert.assertNotNull("award sheet", workbook.getSheet("award"));
    Assert.assertNotNull("item sheet", workbook.getSheet("item"));
    Assert.assertNotNull("contract sheet", workbook.getSheet("contract"));
    Assert.assertEquals("release id", "ocds-213czf-000-00001-01-planning",
            workbook.getSheet("release").getRow(3).getCell(0).toString());
    Assert.assertEquals("release id", "ocds-213czf-000-00001-06-implementation",
            workbook.getSheet("release").getRow(5).getCell(0).toString());
    Assert.assertEquals("tender parent", "release - ocds-213czf-000-00001",
            workbook.getSheet("tender").getRow(1).getCell(0).toString());
    Assert.assertEquals("tender id", "ocds-213czf-000-00001-01-planning",
            workbook.getSheet("tender").getRow(1).getCell(1).toString());
    Assert.assertEquals("award number of rows", 4, workbook.getSheet("award").getLastRowNum());
    Assert.assertEquals("item number of rows", 9, workbook.getSheet("item").getLastRowNum());
    Assert.assertEquals("contract flatten organization id", "E09000003 | E09000003",
            workbook.getSheet("contract").getRow(2).getCell(17).toString());
}