`web/charts`: Migrate to null safety (#921)

web/charts/lib/a11y/domain_a11y_explore_bar_chart.dart

@@ -38,10 +38,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class DomainA11yExploreBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DomainA11yExploreBarChart(this.seriesList, {this.animate, Key key})
+  const DomainA11yExploreBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/app_config.dart

@@ -22,8 +22,12 @@ class AppConfig {
   final ThemeData theme;
   final bool showPerformanceOverlay;
 
-  AppConfig(
+  AppConfig({
-      {this.appName, this.appLink, this.theme, this.showPerformanceOverlay});
+    required this.appName,
+    required this.appLink,
+    required this.theme,
+    required this.showPerformanceOverlay,
+  });
 }
 
 /// The default configuration of the app.

web/charts/lib/axes/bar_secondary_axis.dart

@@ -36,10 +36,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// RTL.flipAxisLocations is set.
 class BarChartWithSecondaryAxis extends StatelessWidget {
   static const secondaryMeasureAxisId = 'secondaryMeasureAxisId';
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const BarChartWithSecondaryAxis(this.seriesList, {this.animate, Key key})
+  const BarChartWithSecondaryAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory BarChartWithSecondaryAxis.withSampleData() {

web/charts/lib/axes/bar_secondary_axis_only.dart

@@ -30,10 +30,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// RTL.flipAxisLocations is set.
 class BarChartWithSecondaryAxisOnly extends StatelessWidget {
   static const secondaryMeasureAxisId = 'secondaryMeasureAxisId';
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const BarChartWithSecondaryAxisOnly(this.seriesList, {this.animate, Key key})
+  const BarChartWithSecondaryAxisOnly(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory BarChartWithSecondaryAxisOnly.withSampleData() {

web/charts/lib/axes/custom_axis_tick_formatters.dart

@@ -22,10 +22,10 @@ import 'package:flutter/material.dart';
 import 'package:intl/intl.dart';
 
 class CustomAxisTickFormatters extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const CustomAxisTickFormatters(this.seriesList, {this.animate, Key key})
+  const CustomAxisTickFormatters(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/axes/custom_font_size_and_color.dart

@@ -26,10 +26,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// There are many axis styling options in the SmallTickRenderer allowing you
 /// to customize the font, tick lengths, and offsets.
 class CustomFontSizeAndColor extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const CustomFontSizeAndColor(this.seriesList, {this.animate, Key key})
+  const CustomFontSizeAndColor(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory CustomFontSizeAndColor.withSampleData() {

web/charts/lib/axes/custom_measure_tick_count.dart

@@ -25,10 +25,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class CustomMeasureTickCount extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const CustomMeasureTickCount(this.seriesList, {this.animate, Key key})
+  const CustomMeasureTickCount(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/axes/flipped_vertical_axis.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// Note: primary and secondary may flip left and right positioning when
 /// RTL.flipAxisLocations is set.
 class FlippedVerticalAxis extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const FlippedVerticalAxis(this.seriesList, {this.animate, Key key})
+  const FlippedVerticalAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory FlippedVerticalAxis.withSampleData() {

web/charts/lib/axes/gridline_dash_pattern.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class GridlineDashPattern extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GridlineDashPattern(this.seriesList, {this.animate, Key key})
+  const GridlineDashPattern(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/axes/hidden_ticks_and_labels_axis.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 
 /// Example of hiding both axis.
 class HiddenTicksAndLabelsAxis extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const HiddenTicksAndLabelsAxis(this.seriesList, {this.animate, Key key})
+  const HiddenTicksAndLabelsAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory HiddenTicksAndLabelsAxis.withSampleData() {

web/charts/lib/axes/horizontal_bar_secondary_axis.dart

@@ -36,11 +36,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// RTL.flipAxisLocations is set.
 class HorizontalBarChartWithSecondaryAxis extends StatelessWidget {
   static const secondaryMeasureAxisId = 'secondaryMeasureAxisId';
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const HorizontalBarChartWithSecondaryAxis(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory HorizontalBarChartWithSecondaryAxis.withSampleData() {

web/charts/lib/axes/integer_only_measure_axis.dart

@@ -26,10 +26,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class IntegerOnlyMeasureAxis extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const IntegerOnlyMeasureAxis(this.seriesList, {this.animate, Key key})
+  const IntegerOnlyMeasureAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/axes/line_disjoint_axis.dart

@@ -28,10 +28,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class DisjointMeasureAxisLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DisjointMeasureAxisLineChart(this.seriesList, {this.animate, Key key})
+  const DisjointMeasureAxisLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
@@ -263,8 +263,8 @@ class DisjointMeasureAxisLineChart extends StatelessWidget {
 /// Sample linear data type.
 class LinearClicks {
   final int year;
-  final int clickCount;
+  final int? clickCount;
-  final double clickRate;
+  final double? clickRate;
 
   LinearClicks(this.year, {this.clickCount, this.clickRate});
 }

web/charts/lib/axes/measure_axis_label_alignment.dart

@@ -23,10 +23,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// Example of using a custom primary measure replacing the renderSpec with one
 /// that aligns the text under the tick and left justifies.
 class MeasureAxisLabelAlignment extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const MeasureAxisLabelAlignment(this.seriesList, {this.animate, Key key})
+  const MeasureAxisLabelAlignment(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory MeasureAxisLabelAlignment.withSampleData() {

web/charts/lib/axes/nonzero_bound_measure_axis.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class NonzeroBoundMeasureAxis extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const NonzeroBoundMeasureAxis(this.seriesList, {this.animate, Key key})
+  const NonzeroBoundMeasureAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/axes/numeric_initial_viewport.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class NumericInitialViewport extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const NumericInitialViewport(this.seriesList, {this.animate, Key key})
+  const NumericInitialViewport(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/axes/ordinal_initial_viewport.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class OrdinalInitialViewport extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const OrdinalInitialViewport(this.seriesList, {this.animate, Key key})
+  const OrdinalInitialViewport(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/axes/short_tick_length_axis.dart

@@ -27,10 +27,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// There are many axis styling options in the SmallTickRenderer allowing you
 /// to customize the font, tick lengths, and offsets.
 class ShortTickLengthAxis extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const ShortTickLengthAxis(this.seriesList, {this.animate, Key key})
+  const ShortTickLengthAxis(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory ShortTickLengthAxis.withSampleData() {

web/charts/lib/axes/statically_provided_ticks.dart

@@ -34,10 +34,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// For datetime axis, the [StaticDateTimeTickProviderSpec] can be used by
 /// passing in a list of ticks defined with [TickSpec] of datetime.
 class StaticallyProvidedTicks extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StaticallyProvidedTicks(this.seriesList, {this.animate, Key key})
+  const StaticallyProvidedTicks(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory StaticallyProvidedTicks.withSampleData() {

web/charts/lib/bar_chart/custom_rounded_bars.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class CustomRoundedBars extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const CustomRoundedBars(this.seriesList, {this.animate, Key key})
+  const CustomRoundedBars(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with custom rounded bars.

web/charts/lib/bar_chart/grouped.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class GroupedBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GroupedBarChart(this.seriesList, {this.animate, Key key})
+  const GroupedBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedBarChart.withSampleData() {

web/charts/lib/bar_chart/grouped_fill_color.dart

@@ -23,10 +23,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// Example of a grouped bar chart with three series, each rendered with
 /// different fill colors.
 class GroupedFillColorBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GroupedFillColorBarChart(this.seriesList, {this.animate, Key key})
+  const GroupedFillColorBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedFillColorBarChart.withSampleData() {

web/charts/lib/bar_chart/grouped_single_target_line.dart

@@ -21,11 +21,11 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class GroupedBarSingleTargetLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const GroupedBarSingleTargetLineChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedBarSingleTargetLineChart.withSampleData() {

web/charts/lib/bar_chart/grouped_stacked.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class GroupedStackedBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GroupedStackedBarChart(this.seriesList, {this.animate, Key key})
+  const GroupedStackedBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedStackedBarChart.withSampleData() {

web/charts/lib/bar_chart/grouped_stacked_weight_pattern.dart

@@ -25,11 +25,11 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class GroupedStackedWeightPatternBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const GroupedStackedWeightPatternBarChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedStackedWeightPatternBarChart.withSampleData() {

web/charts/lib/bar_chart/grouped_target_line.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class GroupedBarTargetLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GroupedBarTargetLineChart(this.seriesList, {this.animate, Key key})
+  const GroupedBarTargetLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory GroupedBarTargetLineChart.withSampleData() {

web/charts/lib/bar_chart/horizontal.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class HorizontalBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const HorizontalBarChart(this.seriesList, {this.animate, Key key})
+  const HorizontalBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/horizontal_bar_label.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class HorizontalBarLabelChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const HorizontalBarLabelChart(this.seriesList, {this.animate, Key key})
+  const HorizontalBarLabelChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/horizontal_bar_label_custom.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class HorizontalBarLabelCustomChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const HorizontalBarLabelCustomChart(this.seriesList, {this.animate, Key key})
+  const HorizontalBarLabelCustomChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/horizontal_pattern_forward_hatch.dart

@@ -25,11 +25,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// The second series of bars is rendered with a pattern by defining a
 /// fillPatternFn mapping function.
 class HorizontalPatternForwardHatchBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const HorizontalPatternForwardHatchBarChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory HorizontalPatternForwardHatchBarChart.withSampleData() {

web/charts/lib/bar_chart/pattern_forward_hatch.dart

@@ -24,10 +24,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PatternForwardHatchBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PatternForwardHatchBarChart(this.seriesList, {this.animate, Key key})
+  const PatternForwardHatchBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory PatternForwardHatchBarChart.withSampleData() {

web/charts/lib/bar_chart/simple.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SimpleBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleBarChart(this.seriesList, {this.animate, Key key})
+  const SimpleBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/spark_bar.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 
 /// Example of a Spark Bar by hiding both axis, reducing the chart margins.
 class SparkBar extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SparkBar(this.seriesList, {this.animate, Key key}) : super(key: key);
+  const SparkBar(this.seriesList, {this.animate, Key? key}) : super(key: key);
 
   factory SparkBar.withSampleData() {
     return SparkBar(

web/charts/lib/bar_chart/stacked.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class StackedBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedBarChart(this.seriesList, {this.animate, Key key})
+  const StackedBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/stacked_fill_color.dart

@@ -23,10 +23,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// Example of a stacked bar chart with three series, each rendered with
 /// different fill colors.
 class StackedFillColorBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedFillColorBarChart(this.seriesList, {this.animate, Key key})
+  const StackedFillColorBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory StackedFillColorBarChart.withSampleData() {

web/charts/lib/bar_chart/stacked_horizontal.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class StackedHorizontalBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedHorizontalBarChart(this.seriesList, {this.animate, Key key})
+  const StackedHorizontalBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/bar_chart/stacked_target_line.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class StackedBarTargetLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedBarTargetLineChart(this.seriesList, {this.animate, Key key})
+  const StackedBarTargetLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/behaviors/chart_title.dart

@@ -23,10 +23,10 @@ import 'package:flutter/material.dart';
 /// A series of [ChartTitle] behaviors are used to render titles, one per
 /// margin.
 class ChartTitleLine extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const ChartTitleLine(this.seriesList, {this.animate, Key key})
+  const ChartTitleLine(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/initial_hint_animation.dart

@@ -48,10 +48,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class InitialHintAnimation extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const InitialHintAnimation(this.seriesList, {this.animate, Key key})
+  const InitialHintAnimation(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/initial_selection.dart

@@ -31,10 +31,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class InitialSelection extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const InitialSelection(this.seriesList, {this.animate, Key key})
+  const InitialSelection(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with initial selection behavior.

web/charts/lib/behaviors/percent_of_domain.dart

@@ -24,10 +24,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfDomainBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PercentOfDomainBarChart(this.seriesList, {this.animate, Key key})
+  const PercentOfDomainBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/behaviors/percent_of_domain_by_category.dart

@@ -25,11 +25,11 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfDomainByCategoryBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const PercentOfDomainByCategoryBarChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory PercentOfDomainByCategoryBarChart.withSampleData() {

web/charts/lib/behaviors/percent_of_series.dart

@@ -22,10 +22,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfSeriesBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PercentOfSeriesBarChart(this.seriesList, {this.animate, Key key})
+  const PercentOfSeriesBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/behaviors/selection_bar_highlight.dart

@@ -19,10 +19,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionBarHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SelectionBarHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionBarHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/selection_callback_example.dart

@@ -33,10 +33,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionCallbackExample extends StatefulWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SelectionCallbackExample(this.seriesList, {this.animate, Key key})
+  const SelectionCallbackExample(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [charts.TimeSeriesChart] with sample data and no transition.
@@ -130,8 +130,8 @@ class SelectionCallbackExample extends StatefulWidget {
 }
 
 class _SelectionCallbackState extends State<SelectionCallbackExample> {
-  DateTime _time;
+  DateTime? _time;
-  Map<String, num> _measures;
+  Map<String?, num?>? _measures;
 
   // Listens to the underlying selection changes, and updates the information
   // relevant to building the primitive legend like information under the
@@ -139,8 +139,8 @@ class _SelectionCallbackState extends State<SelectionCallbackExample> {
   _onSelectionChanged(charts.SelectionModel model) {
     final selectedDatum = model.selectedDatum;
 
-    DateTime time;
+    DateTime? time;
-    final measures = <String, num>{};
+    final measures = <String?, num?>{};
 
     // We get the model that updated with a list of [SeriesDatum] which is
     // simply a pair of series & datum.
@@ -185,7 +185,7 @@ class _SelectionCallbackState extends State<SelectionCallbackExample> {
           padding: const EdgeInsets.only(top: 5.0),
           child: Text(_time.toString())));
     }
-    _measures?.forEach((String series, num value) {
+    _measures?.forEach((String? series, num? value) {
       children.add(Text('$series: $value'));
     });
 

web/charts/lib/behaviors/selection_line_highlight.dart

@@ -19,10 +19,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionLineHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SelectionLineHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionLineHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/selection_line_highlight_custom_shape.dart

@@ -19,11 +19,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionLineHighlightCustomShape extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const SelectionLineHighlightCustomShape(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/selection_scatter_plot_highlight.dart

@@ -38,10 +38,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionScatterPlotHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SelectionScatterPlotHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionScatterPlotHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.
@@ -225,9 +225,9 @@ class LinearSales {
   final int year;
   final int sales;
   final double radius;
-  final String shape;
+  final String? shape;
-  final charts.Color fillColor;
+  final charts.Color? fillColor;
-  final double strokeWidth;
+  final double? strokeWidth;
 
   LinearSales(this.year, this.sales, this.radius, this.shape, this.fillColor,
       this.strokeWidth);

web/charts/lib/behaviors/selection_user_managed.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionUserManaged extends StatefulWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SelectionUserManaged(this.seriesList, {this.animate, Key key})
+  const SelectionUserManaged(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/slider.dart

@@ -33,10 +33,10 @@ import 'package:flutter/scheduler.dart';
 /// [Slider.moveSliderToDomain] can be called to programmatically position the
 /// slider. This is useful for synchronizing the slider with external elements.
 class SliderLine extends StatefulWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SliderLine(this.seriesList, {this.animate, Key key}) : super(key: key);
+  const SliderLine(this.seriesList, {this.animate, Key? key}) : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
   factory SliderLine.withSampleData() {
@@ -103,9 +103,9 @@ class SliderLine extends StatefulWidget {
 }
 
 class _SliderCallbackState extends State<SliderLine> {
-  num _sliderDomainValue;
+  num? _sliderDomainValue;
-  String _sliderDragState;
+  String? _sliderDragState;
-  Point<int> _sliderPosition;
+  Point<int>? _sliderPosition;
 
   // Handles callbacks when the user drags the slider.
   _onSliderChange(Point<int> point, dynamic domain, String roleId,
@@ -119,7 +119,7 @@ class _SliderCallbackState extends State<SliderLine> {
       });
     }
 
-    SchedulerBinding.instance.addPostFrameCallback(rebuild);
+    SchedulerBinding.instance!.addPostFrameCallback(rebuild);
   }
 
   @override
@@ -175,7 +175,7 @@ class _SliderCallbackState extends State<SliderLine> {
       children.add(Padding(
           padding: const EdgeInsets.only(top: 5.0),
           child: Text(
-              'Slider position: ${_sliderPosition.x}, ${_sliderPosition.y}')));
+              'Slider position: ${_sliderPosition!.x}, ${_sliderPosition!.y}')));
     }
     if (_sliderDragState != null) {
       children.add(Padding(

web/charts/lib/behaviors/sliding_viewport_on_selection.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SlidingViewportOnSelection extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SlidingViewportOnSelection(this.seriesList, {this.animate, Key key})
+  const SlidingViewportOnSelection(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/combo_chart/date_time_line_point.dart

@@ -27,10 +27,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class DateTimeComboLinePointChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DateTimeComboLinePointChart(this.seriesList, {this.animate, Key key})
+  const DateTimeComboLinePointChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/combo_chart/numeric_line_bar.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class NumericComboLineBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const NumericComboLineBarChart(this.seriesList, {this.animate, Key key})
+  const NumericComboLineBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/combo_chart/numeric_line_point.dart

@@ -27,10 +27,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class NumericComboLinePointChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const NumericComboLinePointChart(this.seriesList, {this.animate, Key key})
+  const NumericComboLinePointChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/combo_chart/ordinal_bar_line.dart

@@ -22,10 +22,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class OrdinalComboBarLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const OrdinalComboBarLineChart(this.seriesList, {this.animate, Key key})
+  const OrdinalComboBarLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory OrdinalComboBarLineChart.withSampleData() {

web/charts/lib/combo_chart/scatter_plot_line.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class ScatterPlotComboLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const ScatterPlotComboLineChart(this.seriesList, {this.animate, Key key})
+  const ScatterPlotComboLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.

web/charts/lib/drawer.dart

@@ -21,9 +21,9 @@ class GalleryDrawer extends StatelessWidget {
   final ValueChanged<bool> onShowPerformanceOverlayChanged;
 
   const GalleryDrawer(
-      {Key key,
+      {Key? key,
-      this.showPerformanceOverlay,
+      required this.showPerformanceOverlay,
-      this.onShowPerformanceOverlayChanged})
+      required this.onShowPerformanceOverlayChanged})
       : super(key: key);
 
   @override
@@ -40,7 +40,7 @@ class GalleryDrawer extends StatelessWidget {
           selected: showPerformanceOverlay,
           trailing: Checkbox(
             value: showPerformanceOverlay,
-            onChanged: (bool value) {
+            onChanged: (bool? value) {
               onShowPerformanceOverlayChanged(!showPerformanceOverlay);
             },
           ),

web/charts/lib/gallery_scaffold.dart

@@ -20,17 +20,17 @@ typedef GalleryWidgetBuilder = Widget Function();
 /// Helper to build gallery.
 class GalleryScaffold extends StatefulWidget {
   /// The widget used for leading in a [ListTile].
-  final Widget listTileIcon;
+  final Widget? listTileIcon;
   final String title;
   final String subtitle;
   final GalleryWidgetBuilder childBuilder;
 
   const GalleryScaffold(
       {this.listTileIcon,
-      this.title,
+      required this.title,
-      this.subtitle,
+      required this.subtitle,
-      this.childBuilder,
+      required this.childBuilder,
-      Key key})
+      Key? key})
       : super(key: key);
 
   /// Gets the gallery

web/charts/lib/home.dart

@@ -51,12 +51,10 @@ class Home extends StatelessWidget {
   final legendsGalleries = legends.buildGallery();
 
   Home(
-      {Key key,
+      {Key? key,
-      this.showPerformanceOverlay,
+      required this.showPerformanceOverlay,
-      @required this.onShowPerformanceOverlayChanged})
+      required this.onShowPerformanceOverlayChanged})
-      : super(key: key) {
+      : super(key: key);
-    assert(onShowPerformanceOverlayChanged != null);
-  }
 
   @override
   Widget build(BuildContext context) {

web/charts/lib/i18n/rtl_bar_chart.dart

@@ -21,10 +21,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class RTLBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const RTLBarChart(this.seriesList, {this.animate, Key key}) : super(key: key);
+  const RTLBarChart(this.seriesList, {this.animate, Key? key})
+      : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.
   factory RTLBarChart.withSampleData() {

web/charts/lib/i18n/rtl_line_chart.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class RTLLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const RTLLineChart(this.seriesList, {this.animate, Key key})
+  const RTLLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/i18n/rtl_line_segments.dart

@@ -32,10 +32,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class RTLLineSegments extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const RTLLineSegments(this.seriesList, {this.animate, Key key})
+  const RTLLineSegments(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
@@ -242,7 +242,7 @@ class RTLLineSegments extends StatelessWidget {
 class LinearSales {
   final int year;
   final int sales;
-  final List<int> dashPattern;
+  final List<int>? dashPattern;
   final double strokeWidthPx;
 
   LinearSales(this.year, this.sales, this.dashPattern, this.strokeWidthPx);

web/charts/lib/i18n/rtl_series_legend.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class RTLSeriesLegend extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const RTLSeriesLegend(this.seriesList, {this.animate, Key key})
+  const RTLSeriesLegend(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/legends/datum_legend_options.dart

@@ -25,10 +25,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class DatumLegendOptions extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DatumLegendOptions(this.seriesList, {this.animate, Key key})
+  const DatumLegendOptions(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory DatumLegendOptions.withSampleData() {

web/charts/lib/legends/datum_legend_with_measures.dart

@@ -29,9 +29,9 @@ import 'package:charts_flutter/flutter.dart' as charts;
 /// Also shows the option to provide a custom measure formatter.
 class DatumLegendWithMeasures extends StatelessWidget {
   final List<charts.Series<LinearSales, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DatumLegendWithMeasures(this.seriesList, {this.animate, Key key})
+  const DatumLegendWithMeasures(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory DatumLegendWithMeasures.withSampleData() {
@@ -110,7 +110,7 @@ class DatumLegendWithMeasures extends StatelessWidget {
           legendDefaultMeasure: charts.LegendDefaultMeasure.firstValue,
           // Optionally provide a measure formatter to format the measure value.
           // If none is specified the value is formatted as a decimal.
-          measureFormatter: (num value) {
+          measureFormatter: (num? value) {
             return value == null ? '-' : '${value}k';
           },
         ),

web/charts/lib/legends/default_hidden_series_legend.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class DefaultHiddenSeriesLegend extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DefaultHiddenSeriesLegend(this.seriesList, {this.animate, Key key})
+  const DefaultHiddenSeriesLegend(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory DefaultHiddenSeriesLegend.withSampleData() {

web/charts/lib/legends/legend_custom_symbol.dart

@@ -30,11 +30,11 @@ class IconRenderer extends charts.CustomSymbolRenderer {
 
   @override
   Widget build(BuildContext context,
-      {Size size, Color color, bool enabled = true}) {
+      {Size? size, Color? color, bool enabled = true}) {
     // Lighten the color if the symbol is not enabled
     // Example: If user has tapped on a Series deselecting it.
     if (!enabled) {
-      color = color.withOpacity(0.26);
+      color = color!.withOpacity(0.26);
     }
 
     return SizedBox.fromSize(
@@ -43,10 +43,10 @@ class IconRenderer extends charts.CustomSymbolRenderer {
 }
 
 class LegendWithCustomSymbol extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LegendWithCustomSymbol(this.seriesList, {this.animate, Key key})
+  const LegendWithCustomSymbol(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory LegendWithCustomSymbol.withSampleData() {

web/charts/lib/legends/series_legend_options.dart

@@ -25,10 +25,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class LegendOptions extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LegendOptions(this.seriesList, {this.animate, Key key})
+  const LegendOptions(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory LegendOptions.withSampleData() {

web/charts/lib/legends/series_legend_with_measures.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 ///
 /// Also shows the option to provide a custom measure formatter.
 class LegendWithMeasures extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LegendWithMeasures(this.seriesList, {this.animate, Key key})
+  const LegendWithMeasures(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory LegendWithMeasures.withSampleData() {
@@ -153,7 +153,7 @@ class LegendWithMeasures extends StatelessWidget {
           showMeasures: true,
           // Optionally provide a measure formatter to format the measure value.
           // If none is specified the value is formatted as a decimal.
-          measureFormatter: (num value) {
+          measureFormatter: (num? value) {
             return value == null ? '-' : '${value}k';
           },
         ),

web/charts/lib/legends/simple_datum_legend.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class SimpleDatumLegend extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleDatumLegend(this.seriesList, {this.animate, Key key})
+  const SimpleDatumLegend(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory SimpleDatumLegend.withSampleData() {

web/charts/lib/legends/simple_series_legend.dart

@@ -21,10 +21,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class SimpleSeriesLegend extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleSeriesLegend(this.seriesList, {this.animate, Key key})
+  const SimpleSeriesLegend(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   factory SimpleSeriesLegend.withSampleData() {

web/charts/lib/line_chart/animation_zoom.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class LineAnimationZoomChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LineAnimationZoomChart(this.seriesList, {this.animate, Key key})
+  const LineAnimationZoomChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/area_and_line.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class AreaAndLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const AreaAndLineChart(this.seriesList, {this.animate, Key key})
+  const AreaAndLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/dash_pattern.dart

@@ -22,10 +22,10 @@ import 'package:flutter/material.dart';
 
 /// Example of a line chart rendered with dash patterns.
 class DashPatternLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DashPatternLineChart(this.seriesList, {this.animate, Key key})
+  const DashPatternLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/line_annotation.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class LineLineAnnotationChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LineLineAnnotationChart(this.seriesList, {this.animate, Key key})
+  const LineLineAnnotationChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and line annotations.

web/charts/lib/line_chart/points.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class PointsLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PointsLineChart(this.seriesList, {this.animate, Key key})
+  const PointsLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/range_annotation.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class LineRangeAnnotationChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LineRangeAnnotationChart(this.seriesList, {this.animate, Key key})
+  const LineRangeAnnotationChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and range annotations.

web/charts/lib/line_chart/range_annotation_margin.dart

@@ -22,10 +22,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class LineRangeAnnotationMarginChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const LineRangeAnnotationMarginChart(this.seriesList, {this.animate, Key key})
+  const LineRangeAnnotationMarginChart(this.seriesList,
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and range annotations.

web/charts/lib/line_chart/segments.dart

@@ -32,10 +32,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SegmentsLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SegmentsLineChart(this.seriesList, {this.animate, Key key})
+  const SegmentsLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
@@ -227,7 +227,7 @@ class SegmentsLineChart extends StatelessWidget {
 class LinearSales {
   final int year;
   final int sales;
-  final List<int> dashPattern;
+  final List<int>? dashPattern;
   final double strokeWidthPx;
 
   LinearSales(this.year, this.sales, this.dashPattern, this.strokeWidthPx);

web/charts/lib/line_chart/simple.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SimpleLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleLineChart(this.seriesList, {this.animate, Key key})
+  const SimpleLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/simple_nulls.dart

@@ -25,10 +25,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SimpleNullsLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleNullsLineChart(this.seriesList, {this.animate, Key key})
+  const SimpleNullsLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
@@ -174,7 +174,7 @@ class SimpleNullsLineChart extends StatelessWidget {
 /// Sample linear data type.
 class LinearSales {
   final int year;
-  final int sales;
+  final int? sales;
 
   LinearSales(this.year, this.sales);
 }

web/charts/lib/line_chart/stacked_area.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class StackedAreaLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedAreaLineChart(this.seriesList, {this.animate, Key key})
+  const StackedAreaLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/stacked_area_custom_color.dart

@@ -25,11 +25,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class StackedAreaCustomColorLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const StackedAreaCustomColorLineChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/line_chart/stacked_area_nulls.dart

@@ -34,10 +34,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class StackedAreaNullsLineChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const StackedAreaNullsLineChart(this.seriesList, {this.animate, Key key})
+  const StackedAreaNullsLineChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
@@ -186,7 +186,7 @@ class StackedAreaNullsLineChart extends StatelessWidget {
 /// Sample linear data type.
 class LinearSales {
   final int year;
-  final int sales;
+  final int? sales;
 
   LinearSales(this.year, this.sales);
 }

web/charts/lib/main.dart

@@ -19,7 +19,7 @@ import 'home.dart';
 
 /// The main gallery app widget.
 class GalleryApp extends StatefulWidget {
-  const GalleryApp({Key key}) : super(key: key);
+  const GalleryApp({Key? key}) : super(key: key);
 
   @override
   GalleryAppState createState() => GalleryAppState();

web/charts/lib/pie_chart/auto_label.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class DonutAutoLabelChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DonutAutoLabelChart(this.seriesList, {this.animate, Key key})
+  const DonutAutoLabelChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.

web/charts/lib/pie_chart/donut.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class DonutPieChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const DonutPieChart(this.seriesList, {this.animate, Key key})
+  const DonutPieChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.

web/charts/lib/pie_chart/gauge.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class GaugeChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, String>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const GaugeChart(this.seriesList, {this.animate, Key key}) : super(key: key);
+  const GaugeChart(this.seriesList, {this.animate, Key? key}) : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.
   factory GaugeChart.withSampleData() {

web/charts/lib/pie_chart/outside_label.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class PieOutsideLabelChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PieOutsideLabelChart(this.seriesList, {this.animate, Key key})
+  const PieOutsideLabelChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.

web/charts/lib/pie_chart/partial_pie.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class PartialPieChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const PartialPieChart(this.seriesList, {this.animate, Key key})
+  const PartialPieChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.

web/charts/lib/pie_chart/simple.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SimplePieChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, int>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimplePieChart(this.seriesList, {this.animate, Key key})
+  const SimplePieChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [PieChart] with sample data and no transition.

web/charts/lib/scatter_plot_chart/animation_zoom.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class ScatterPlotAnimationZoomChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const ScatterPlotAnimationZoomChart(this.seriesList, {this.animate, Key key})
+  const ScatterPlotAnimationZoomChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.

web/charts/lib/scatter_plot_chart/bucketing_axis.dart

@@ -26,10 +26,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class BucketingAxisScatterPlotChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const BucketingAxisScatterPlotChart(this.seriesList, {this.animate, Key key})
+  const BucketingAxisScatterPlotChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.

web/charts/lib/scatter_plot_chart/comparison_points.dart

@@ -21,11 +21,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class ComparisonPointsScatterPlotChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
   const ComparisonPointsScatterPlotChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.

web/charts/lib/scatter_plot_chart/shapes.dart

@@ -32,10 +32,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class ShapesScatterPlotChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const ShapesScatterPlotChart(this.seriesList, {this.animate, Key key})
+  const ShapesScatterPlotChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.
@@ -196,9 +196,9 @@ class LinearSales {
   final int year;
   final int sales;
   final double radius;
-  final String shape;
+  final String? shape;
-  final charts.Color fillColor;
+  final charts.Color? fillColor;
-  final double strokeWidth;
+  final double? strokeWidth;
 
   LinearSales(this.year, this.sales, this.radius, this.shape, this.fillColor,
       this.strokeWidth);

web/charts/lib/scatter_plot_chart/simple.dart

@@ -21,10 +21,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SimpleScatterPlotChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, num>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const SimpleScatterPlotChart(this.seriesList, {this.animate, Key key})
+  const SimpleScatterPlotChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.

web/charts/lib/time_series_chart/confidence_interval.dart

@@ -24,10 +24,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class TimeSeriesConfidenceInterval extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const TimeSeriesConfidenceInterval(this.seriesList, {this.animate, Key key})
+  const TimeSeriesConfidenceInterval(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/time_series_chart/end_points_axis.dart

@@ -23,10 +23,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class EndPointsAxisTimeSeriesChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const EndPointsAxisTimeSeriesChart(this.seriesList, {this.animate, Key key})
+  const EndPointsAxisTimeSeriesChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/time_series_chart/line_annotation.dart

@@ -28,10 +28,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class TimeSeriesLineAnnotationChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const TimeSeriesLineAnnotationChart(this.seriesList, {this.animate, Key key})
+  const TimeSeriesLineAnnotationChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.

web/charts/lib/time_series_chart/range_annotation.dart

@@ -28,10 +28,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class TimeSeriesRangeAnnotationChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
-  final bool animate;
+  final bool? animate;
 
-  const TimeSeriesRangeAnnotationChart(this.seriesList, {this.animate, Key key})
+  const TimeSeriesRangeAnnotationChart(this.seriesList,
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [TimeSeriesChart] with sample data and no transition.