@Override
    public DataFormatData clone() {
        DataFormatData dataFormatData = new DataFormatData();
        dataFormatData.setIndex(getIndex());
        dataFormatData.setFormat(getFormat());
        return dataFormatData;
    }
The source is not empty merge the data to the target.

@param source source
@param target target
fastexcel-core/src/main/java/cn/idev/excel/metadata/data/DataFormatData.java