@Override
        public Object parseObject(String source, ParsePosition pos) {
            return df.parseObject(source, pos);
        }
Format class that does nothing and always returns a constant string.

This format is used to simulate Excel's handling of a format string of all # when the value is 0. Excel will
output "", Java will output "0".
fastexcel-test/src/test/java/cn/idev/excel/test/temp/dataformat/DataFormatter1.java