public static ConverterKey buildKey(Class<?> clazz, CellDataTypeEnum cellDataTypeEnum) {
        Class<?> boxingClass = BOXING_MAP.get(clazz);
        if (boxingClass != null) {
            return new ConverterKey(boxingClass, cellDataTypeEnum);
        }
        return new ConverterKey(clazz, cellDataTypeEnum);
    }
Converter unique key.Consider that you can just use class as the key.

@author Jiaju Zhuang
fastexcel-core/src/main/java/cn/idev/excel/converters/ConverterKeyBuild.java