Tooltip 'x' String Repeats for Each Data Point in Line Chart

[omeriakyuz]

Hello,
I am experiencing an issue with the LineTooltipItem in my Flutter project using the fl_chart package. The tooltip displays the time(x) string for each data point, but I want the time string to appear only once at the top of the tooltip. I want it to look like this instead of like the picture below:
"14.00
16.8 °C
15.3 °C"

Here's code snippet and image of current situation:

getTooltipItems: (List<LineBarSpot> touchedBarSpots) {
                    return touchedBarSpots.map((barSpot) {
                      final flSpot = barSpot;


                      return LineTooltipItem(
                        '${flSpot.x.toInt()}:00\n',
                        TextStyle(
                          color: Colors.black,
                          fontWeight: FontWeight.bold,
                        ),
                        children: [
                          TextSpan(
                            text: flSpot.y.toString(),
                            style: TextStyle(
                              color: flSpot.bar.color,
                              fontWeight: FontWeight.w900,
                            ),
                          ),
                          TextSpan(
                            text: ' °C ',
                            style: TextStyle(
                              color: flSpot.bar.color,
                              fontStyle: FontStyle.italic,
                              fontWeight: FontWeight.w900,
                            ),
                          ),
                        ],
                      );
                    }).toList();
                  },

Additional information: I tried to define value for time string and insert it to TooltipItems list as first item. But It threw this "Exception: tooltipItems and touchedSpots size should be same". Code for this one:

                 getTooltipItems: (List<LineBarSpot> touchedBarSpots) {
                    final xValue = touchedBarSpots.first.x.toInt();
                    final timeString = '${xValue.toString().padLeft(2, '0')}:00';
                    final tooltipItems = touchedBarSpots.map((barSpot) {
                      final flSpot = barSpot;
                      return LineTooltipItem(
                        '',
                        TextStyle(
                          color: Colors.black,
                          fontWeight: FontWeight.bold,
                        ),
                        children: [
                          TextSpan(
                            text: flSpot.y.toString(),
                            style: TextStyle(
                              color: flSpot.bar.color,
                              fontWeight: FontWeight.w900,
                            ),
                          ),
                          TextSpan(
                            text: ' °C ',
                            style: TextStyle(
                              color: flSpot.bar.color,
                              fontStyle: FontStyle.italic,
                              fontWeight: FontWeight.w900,
                            ),
                          ),
                        ],
                      );
                    }).toList();

                    tooltipItems.insert(0, LineTooltipItem(timeString, const TextStyle(color: Colors.black, fontWeight: FontWeight.bold, fontSize: 9)));
                    return tooltipItems;
                  },