title: Flutter: Stream not retrieving data from sub collection
body: <p>I am creating my own comment system.
  I am using firebase to store the comments and then the replies into a subcollection.
  My code is retrieving the main comments, but for some reason I can't get the sub comments.
  Have double checked the path and everything.</p>
  <p>My stream looks like this</p>
  <pre><code>    var retVal;
      try {
          retVal = FirebaseFirestore.instance
            .collection('Challenges')
            .doc(challenge.id)
            .collection('comments')
            .doc(comment.id)
            .collection('SubComments')
            .orderBy(CommentField.createdTime, descending: true)
            .snapshots()
            .transform(Utils.transformer&lt;Comment&gt;(Comment.fromJson));
        return retVal;
      } on FirebaseException catch (e)
      {
        print(e.toString());
        return retVal;
  
      }
    }
  </code></pre>
  <p>(mind the var and other weird stuff. Was trying to see if i can catch a error, but no luck)</p>
  <p>Code where I call the stream using Riverpod.</p>
  <pre><code>final challengeSubCommentStreamProvider =
  StreamProvider.autoDispose.family&lt;List&lt;Comment&gt;, ReadSubCommentClass&gt;((ref, parameters) {
    final database = ref.watch(databaseProvider);
    return database.readSubComments(parameters.challenge, parameters.comment);
  });
  
      return Consumer(
        builder: (context, ScopedReader watch, child){
          final userDataProvider = watch(userProvider);
          final user = userDataProvider.user;
          final ReadSubCommentClass parameters = ReadSubCommentClass(challenge: widget.challenge, comment: widget.comment!);
          final challengeSubCommentStream = watch(challengeSubCommentStreamProvider(parameters));
          return challengeSubCommentStream.when(
              data: (comments) {
                if(comments.isNotEmpty)
                return SliverList(
                  delegate: SliverChildBuilderDelegate(
                        (context, int index){
                      return buildReplyCommentListTile(comments[index], user);
                    },
                    childCount: comments.length,
                  ),
                );
                else return Container(color: Colors.blue,);
              },
              loading: () =&gt; SliverToBoxAdapter(child: Center(child: Text('Loading'),)),
              error: (_,__) =&gt; SliverToBoxAdapter(child: Container()));
        },
      );
  </code></pre>
  <p>Picture from Firestore to depict path
  Challenges/{ChallengeID}/comments/{CommentID}/SubComments</p>
  <p><a href="https://i.stack.imgur.com/w7jpP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/w7jpP.png" alt="enter image description here" /></a>
  The code is just stuck at Loading and not getting any values.</p>