spring batch execution，如何避免文件名为空的FlatFileItemWriter引发日志异常

@Bean
public FlatFileItemWriter<MyObject> itemWriter() {
    FlatFileItemWriter<MyObject> writer = new FlatFileItemWriter<>();
    writer.setResource(new FileSystemResource("output.txt"));
    writer.setLineAggregator(new PassThroughLineAggregator<>());
    writer.setShouldDeleteIfExists(true);
    writer.setAppendAllowed(true);
    writer.setEncoding("UTF-8");
    writer.setLineSeparator(System.lineSeparator());
    writer.setFileNameGenerator(new UniqueFileNameGenerator());
    return writer;
}

@Override
public void write(List<? extends MyObject> items) throws Exception {
    if (StringUtils.isEmpty(fileName)) {
        throw new IllegalArgumentException("File name cannot be empty.");
    }
    // 写入数据到文件
}