title: Flutter PagedListView not keep dynamic widgets when rendering
body: <p>I'm new to flutter, I use <code>PageListView</code> for listing large data set from the backend <a href="https://pub.dev/packages/infinite_scroll_pagination" rel="nofollow noreferrer">infinite_scroll_pagination</a>. and I need to group data set by date so I try to add the date using Text widget inside the PageListView widgets. but when load next page, I added Text widgets disappear here is my code, please suggest me the solution</p>
  <p>part of the build method</p>
  <pre class="lang-dart prettyprint-override"><code> Expanded(
                  child: Container(
                    padding: const EdgeInsets.only(bottom: 10.0),
                    child: PagedListView&lt;int, Content&gt;(
                        pagingController: _pagingController,
                        builderDelegate: PagedChildBuilderDelegate&lt;Content&gt;(
                            itemBuilder: (context, item, index) {
                          bool _flag = false;
                          if (!_dateMap.containsKey(item.date.toString())) {
                            _dateMap.putIfAbsent(
                                item.date.toString(), () =&gt; item.date);
                            _flag = true;
                          }
                          return Column(
                            children: [
                              Visibility(
                                visible: _flag,
                                child: Container(
                                  margin: EdgeInsets.only(top: 15, bottom: 15),
                                  child: Center(
                                    child: Text(
                                      item.date
                                                  .difference(DateTime.now())
                                                  .inDays ==
                                              0
                                          ? 'Today'
                                          : item.date
                                                      .difference(DateTime.now())
                                                      .inDays ==
                                                  -1
                                              ? 'Yesterday'
                                              : DateFormat('dd-MMM-yyyy')
                                                  .format(item.date)
                                                  .toString(),
                                      style:
                                          Theme.of(context).textTheme.subtitle2,
                                    ),
                                  ),
                                ),
                              ),
                              Padding(
                                padding:
                                    const EdgeInsets.only(top: 2.5, bottom: 2.5),
                                child: AccountTitle2(
                                  reference: item.reference.toString(),
                                  accountNo: item.accountNo,
                                  transactionType: item.narration,
                                  //format.parse(item.time)
                                  date: item.date.toString(),
                                  time: item.time,
                                  //format.parse(item.time).toString(),
                                  withdraw: item.withdraw,
                                  deposit: item.deposit,
                                ),
                              )
                            ],
                          );
                        })),
                  ),
                )
  
  </code></pre>
  <p>here is the example output I need</p>
  <pre><code>Today
  
   - Item 1
   - Item 2
   - Item 3
  
  Yesterday 
  
   - Item 4
   - Item 5
   - Item 6
  
  10-10-2020
  
   - Item 7
   - Item 8
   - Item 9
  
  </code></pre>