无法使用documents4j将xlsx文件转换为xls

import org.apache.poi.ss.usermodel.*;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class XlsxToXlsConverter {
    public static void main(String[] args) {
        String xlsxFilePath = "path/to/input.xlsx";
        String xlsFilePath = "path/to/output.xls";

        try (Workbook workbook = WorkbookFactory.create(new FileInputStream(xlsxFilePath));
             FileOutputStream fileOutputStream = new FileOutputStream(xlsFilePath)) {

            // 创建新的xls格式的工作簿
            Workbook xlsWorkbook = new HSSFWorkbook();

            // 遍历xlsx文件中的所有工作表
            for (int i = 0; i < workbook.getNumberOfSheets(); i++) {
                Sheet sheet = workbook.getSheetAt(i);
                Sheet xlsSheet = xlsWorkbook.createSheet(sheet.getSheetName());

                // 复制每个工作表中的行和单元格
                for (int j = 0; j <= sheet.getLastRowNum(); j++) {
                    Row row = sheet.getRow(j);
                    Row xlsRow = xlsSheet.createRow(j);

                    for (int k = 0; k < row.getLastCellNum(); k++) {
                        Cell cell = row.getCell(k);
                        Cell xlsCell = xlsRow.createCell(k);

                        // 复制单元格的值和样式
                        xlsCell.setCellValue(getCellValue(cell));
                        xlsCell.setCellStyle(cell.getCellStyle());
                    }
                }
            }

            // 保存xls文件
            xlsWorkbook.write(fileOutputStream);
            System.out.println("xlsx文件转换为xls文件成功！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static Object getCellValue(Cell cell) {
        Object value = null;

        switch (cell.getCellType()) {
            case STRING:
                value = cell.getStringCellValue();
                break;
            case NUMERIC:
                value = cell.getNumericCellValue();
                break;
            case BOOLEAN:
                value = cell.getBooleanCellValue();
                break;
            case FORMULA:
                value = cell.getCellFormula();
                break;
            default:
                break;
        }

        return value;
    }
}