code: public Map<String, CellStyle> getCellStyleMapping() {
          if (this.cellStyleMapping == null) {
              this.cellStyleMapping = new HashMap<String, CellStyle>(16);
          }
          return cellStyleMapping;
      }
docs: 获取属性名到单元格样式的映射
  
  @return 返回属性名到单元格样式的映射