在SAP UI5中下载时Excel缺少某些列值

Question

当我导出Excel时，某些列值完全为空白。 我检查发现，在前导属性中，我使用了多个字段值，该值显示为一列中的组合。如果我给一个字段值，那么数据就来了。

我曾经这样使用

FutureBuilder(
            future: Firestore.instance.collection("latest").orderBy("date", descending: true)
                .getDocuments(source: Source.serverAndCache ),
            builder: (context, snapshot) {

              if (!snapshot.hasData || snapshot.data.documents.length == null) {
                return Center(
                  child: CircularProgressIndicator(
                    valueColor: AlwaysStoppedAnimation(Colors.white),
                  ),
                );
              } else if(snapshot.data.documents.length == 0) {

                return Center(
                    child: Padding(
                      padding: const EdgeInsets.only(left: 16, right: 16),
                      child: Text(
                        "Sorry but there's no wallpapers for this character yet!",
                        style: TextStyle(
                          fontSize: 16,
                          fontWeight: FontWeight.w300,
                        ),
                        textAlign: TextAlign.center,
                      ),
                    )
                );

              } else {

                return GridView.builder(
                    itemCount: snapshot.data.documents.length,
                    gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                      crossAxisCount: 2,
                      childAspectRatio: screenHeight / screenWidth * 0.4,
                      mainAxisSpacing: 1.0,
                      crossAxisSpacing: 1.0,
                    ),
                    itemBuilder: (context, index) {

                      return _buildGrid(snapshot.data.documents[index], index);

                    }
                );



              }
            }
          )

Widget _buildGrid(DocumentSnapshot document, int index) {

      print(document.metadata.isFromCache ? "NOT FROM NETWORK" : "FROM NETWORK");

      return GestureDetector(
        child: Hero(
          tag: index,
          child: CachedNetworkImage(
            imageUrl: document['url'],
            errorWidget: (context, url, error) => Icon(Icons.error_outline),
            fit: BoxFit.fill,
            filterQuality: FilterQuality.low,

          ),

        ),
        onTap: () {
          Navigator.of(context).push(
              MaterialPageRoute(
                  builder: (context) => DetailScreen(document['url']))
          );
        },
      );
    }

表中的数据很好。但是当导出到excel时，此列值被空白。

有人可以建议我一些答案吗？