[alibaba/easyexcel]已有文件追加sheet页，数据已追加，但文件破损

如果文件不存在，则新建文件，添加第一个sheet页；否则，在该文件中追加sheet页

// 核心代码
    public static <E> void writeModelList(File outputFile, List<E> modelList, int sheetNo, String sheetName) {
        if (CollectionUtils.isEmpty(modelList)) {
            return;
        }
        Class<?> clazz = modelList.get(0).getClass();
        List<ReadSheet> sheets = Collections.emptyList();
        boolean isAppend = false;
        if (outputFile.exists()) {
            isAppend = true;
            ExcelReader excelReader = EasyExcel.read(outputFile).build();
            sheets = excelReader.excelExecutor().sheetList();
            excelReader.close();
        }
        if (sheets.size() > sheetNo) {
            throw new G4cException(String.format(Locale.ROOT, "Invalid sheetNo,must less than or equal %d", sheets.size()));
        }
        if (sheets.stream().anyMatch(st -> st.getSheetName().equalsIgnoreCase(sheetName))) {
            throw new G4cException(String.format(Locale.ROOT, "Sheet name %s already exists.", sheetName));
        }
        if (sheets.size() < sheetNo) {
            sheetNo = sheets.size();
        }
        try (OutputStream outputStream = new FileOutputStream(outputFile, isAppend);
             ExcelWriter excelWriter = EasyExcel.write(outputStream, clazz).build()) {
            int pageCount = modelList.size() / PAGE_SIZE + 1;
            WriteSheet writeSheet = EasyExcel.writerSheet(sheetNo, sheetName).build();
            for (int i = 0; i < pageCount; i++) {
                List<E> pageData = modelList.stream().skip(i * PAGE_SIZE).limit(PAGE_SIZE).collect(Collectors.toList());
                excelWriter.write(pageData, writeSheet);
            }
            excelWriter.finish();
        } catch (Exception exception) {
            log.error("writeModelList=>{}", exception.getMessage());
        }
    }

// UT代码
@Data
@AllArgsConstructor
class DemoData {
    private int num;
    private String text;
}
    @Test
    void writeModelList() {
        File outFile = new File("D:\\temp\\test.xlsx");
        List<DemoData> list = new ArrayList<>(5550);
        for (int i = 0; i < 5550; i++) {
            DemoData demoData = new DemoData(i + 1, "data" + (i + 1));
            list.add(demoData);
        }
        ExcelUtil.writeModelList(outFile, list, 2, "我的sheet1");
    }

第一次创建文件成功， 第二次追加时，文件尺寸变为之前的2倍，符合预期，但是文件打不开。UT中代码中修改sheet页ExcelUtil.writeModelList(outFile, list, 2, "我的sheet2"); ，

打开时出现如下提示：

可见文件破损，修复之后，还是只有追加之前的内容，追加的内容看不到。