Remove 'must be non-null' and 'must not be null' comments from material. (#134991)

## Description

This removes all of the comments that are of the form "so-and-so (must not be null|can ?not be null|must be non-null)" from the cases where those values are defines as non-nullable values.

This PR removes them from the material library.

This was done by hand, since it really didn't lend itself to scripting, so it needs to be more than just spot-checked, I think. I was careful to leave any comment that referred to parameters that were nullable, but I may have missed some.

In addition to being no longer relevant after null safety has been made the default, these comments were largely fragile, in that it was easy for them to get out of date, and not be accurate anymore anyhow.

This did create a number of constructor comments which basically say "Creates a [Foo].", but I don't really know how to avoid that in a large scale change, since there's not much you can really say in a lot of cases.  I think we might consider some leniency for constructors to the "Comment must be meaningful" style guidance (which we de facto have already, since there are a bunch of these).

## Related PRs
- flutter/flutter#134984
- flutter/flutter#134992
- flutter/flutter#134993
- flutter/flutter#134994

## Tests
 - Documentation only change.

Author: gspencergoog

packages/flutter/lib/src/material/animated_icons/animated_icons.dart

@@ -29,8 +29,8 @@ part of material_animated_icons; // ignore: use_string_in_part_of_directives
 class AnimatedIcon extends StatelessWidget {
   /// Creates an AnimatedIcon.
   ///
-  /// The [progress] and [icon] arguments must not be null.
-  /// The [size] and [color] default to the value given by the current [IconTheme].
+  /// The [size] and [color] default to the value given by the current
+  /// [IconTheme].
   const AnimatedIcon({
     super.key,
     required this.icon,

packages/flutter/lib/src/material/app.dart

@@ -202,8 +202,6 @@ class MaterialApp extends StatefulWidget {
   /// unsupported route.
   ///
   /// This class creates an instance of [WidgetsApp].
-  ///
-  /// The boolean arguments, [routes], and [navigatorObservers], must not be null.
   const MaterialApp({
     super.key,
     this.navigatorKey,

packages/flutter/lib/src/material/app_bar.dart

@@ -1436,9 +1436,6 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
 ///  * <https://material.io/design/components/app-bars-top.html>
 class SliverAppBar extends StatefulWidget {
   /// Creates a Material Design app bar that can be placed in a [CustomScrollView].
-  ///
-  /// The arguments [forceElevated], [primary], [floating], [pinned], [snap]
-  /// and [automaticallyImplyLeading] must not be null.
   const SliverAppBar({
     super.key,
     this.leading,

packages/flutter/lib/src/material/app_bar_theme.dart

@@ -200,8 +200,6 @@ class AppBarTheme with Diagnosticable {
 
   /// Linearly interpolate between two AppBar themes.
   ///
-  /// The argument `t` must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static AppBarTheme lerp(AppBarTheme? a, AppBarTheme? b, double t) {
     if (identical(a, b) && a != null) {

packages/flutter/lib/src/material/banner.dart

@@ -93,9 +93,8 @@ enum MaterialBannerClosedReason {
 class MaterialBanner extends StatefulWidget {
   /// Creates a [MaterialBanner].
   ///
-  /// The [actions], [content], and [forceActionsBelow] must be non-null.
-  /// The [actions].length must be greater than 0. The [elevation] must be null or
-  /// non-negative.
+  /// The length of the [actions] list must not be empty. The [elevation] must
+  /// be null or non-negative.
   const MaterialBanner({
     super.key,
     required this.content,

packages/flutter/lib/src/material/banner_theme.dart

@@ -97,8 +97,6 @@ class MaterialBannerThemeData with Diagnosticable {
 
   /// Linearly interpolate between two Banner themes.
   ///
-  /// The argument `t` must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static MaterialBannerThemeData lerp(MaterialBannerThemeData? a, MaterialBannerThemeData? b, double t) {
     return MaterialBannerThemeData(

packages/flutter/lib/src/material/bottom_app_bar_theme.dart

@@ -94,8 +94,6 @@ class BottomAppBarTheme with Diagnosticable {
 
   /// Linearly interpolate between two BAB themes.
   ///
-  /// The argument `t` must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static BottomAppBarTheme lerp(BottomAppBarTheme? a, BottomAppBarTheme? b, double t) {
     if (identical(a, b) && a != null) {

packages/flutter/lib/src/material/bottom_navigation_bar.dart

@@ -80,8 +80,8 @@ enum BottomNavigationBarLandscapeLayout {
 /// [BottomNavigationBarType.fixed] when there are less than four items, and
 /// [BottomNavigationBarType.shifting] otherwise.
 ///
-/// The length of [items] must be at least two and each item's icon and title/label
-/// must not be null.
+/// The length of [items] must be at least two and each item's icon and
+/// label must not be null.
 ///
 ///  * [BottomNavigationBarType.fixed], the default when there are less than
 ///    four [items]. The selected item is rendered with the
@@ -188,7 +188,7 @@ class BottomNavigationBar extends StatefulWidget {
   /// are two or three [items], [BottomNavigationBarType.shifting] otherwise.
   ///
   /// The [iconSize], [selectedFontSize], [unselectedFontSize], and [elevation]
-  /// arguments must be non-null and non-negative.
+  /// arguments must be non-negative.
   ///
   /// If [selectedLabelStyle].color and [unselectedLabelStyle].color values
   /// are non-null, they will be used instead of [selectedItemColor] and

packages/flutter/lib/src/material/bottom_navigation_bar_theme.dart

@@ -170,8 +170,6 @@ class BottomNavigationBarThemeData with Diagnosticable {
 
   /// Linearly interpolate between two [BottomNavigationBarThemeData].
   ///
-  /// The argument `t` must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static BottomNavigationBarThemeData lerp(BottomNavigationBarThemeData? a, BottomNavigationBarThemeData? b, double t) {
     if (identical(a, b) && a != null) {
@@ -276,8 +274,6 @@ class BottomNavigationBarThemeData with Diagnosticable {
 class BottomNavigationBarTheme extends InheritedWidget {
   /// Constructs a bottom navigation bar theme that configures all descendant
   /// [BottomNavigationBar] widgets.
-  ///
-  /// The [data] must not be null.
   const BottomNavigationBarTheme({
     super.key,
     required this.data,

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -1133,8 +1133,6 @@ class ModalBottomSheetRoute<T> extends PopupRoute<T> {
 /// curve specified with the [curve] argument, after the finger is released. In
 /// such a case, the value of [startingPoint] would be the progress of the
 /// animation at the time when the finger was released.
-///
-/// The [startingPoint] and [curve] arguments must not be null.
 class _BottomSheetSuspendedCurve extends ParametricCurve<double> {
   /// Creates a suspended curve.
   const _BottomSheetSuspendedCurve(

packages/flutter/lib/src/material/button.dart

@@ -40,11 +40,8 @@ import 'theme_data.dart';
 class RawMaterialButton extends StatefulWidget {
   /// Create a button based on [Semantics], [Material], and [InkWell] widgets.
   ///
-  /// The [shape], [elevation], [focusElevation], [hoverElevation],
-  /// [highlightElevation], [disabledElevation], [padding], [constraints],
-  /// [autofocus], and [clipBehavior] arguments must not be null. Additionally,
-  /// [elevation], [focusElevation], [hoverElevation], [highlightElevation], and
-  /// [disabledElevation] must be non-negative.
+  /// The [elevation], [focusElevation], [hoverElevation], [highlightElevation],
+  /// and [disabledElevation] parameters must be non-negative.
   const RawMaterialButton({
     super.key,
     required this.onPressed,
@@ -288,7 +285,7 @@ class RawMaterialButton extends StatefulWidget {
 
   /// {@macro flutter.material.Material.clipBehavior}
   ///
-  /// Defaults to [Clip.none], and must not be null.
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   /// Whether detected gestures should provide acoustic and/or haptic feedback.

packages/flutter/lib/src/material/button_bar_theme.dart

@@ -233,8 +233,6 @@ class ButtonBarThemeData with Diagnosticable {
 class ButtonBarTheme extends InheritedWidget {
   /// Constructs a button bar theme that configures all descendent [ButtonBar]
   /// widgets.
-  ///
-  /// The [data] must not be null.
   const ButtonBarTheme({
     super.key,
     required this.data,

packages/flutter/lib/src/material/button_style_button.dart

@@ -89,7 +89,7 @@ abstract class ButtonStyleButton extends StatefulWidget {
 
   /// {@macro flutter.material.Material.clipBehavior}
   ///
-  /// Defaults to [Clip.none], and must not be null.
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   /// {@macro flutter.widgets.Focus.focusNode}

packages/flutter/lib/src/material/button_theme.dart

@@ -66,9 +66,6 @@ enum ButtonBarLayoutBehavior {
 ///    depend on any inherited themes.
 class ButtonTheme extends InheritedTheme {
   /// Creates a button theme.
-  ///
-  /// The [textTheme], [minWidth], [height], and [colorScheme] arguments
-  /// must not be null.
   ButtonTheme({
     super.key,
     ButtonTextTheme textTheme = ButtonTextTheme.normal,
@@ -108,8 +105,6 @@ class ButtonTheme extends InheritedTheme {
        );
 
   /// Creates a button theme from [data].
-  ///
-  /// The [data] argument must not be null.
   const ButtonTheme.fromButtonThemeData({
     super.key,
     required this.data,
@@ -168,9 +163,7 @@ class ButtonThemeData with Diagnosticable {
   /// Create a button theme object that can be used with [ButtonTheme]
   /// or [ThemeData].
   ///
-  /// The [textTheme], [minWidth], [height], [alignedDropdown], and
-  /// [layoutBehavior] parameters must not be null. The [minWidth] and
-  /// [height] parameters must greater than or equal to zero.
+  /// The [minWidth] and [height] parameters must greater than or equal to zero.
   ///
   /// The ButtonTheme's methods that have a [MaterialButton] parameter and
   /// have a name with a `get` prefix are used to configure a

packages/flutter/lib/src/material/calendar_date_picker.dart

@@ -1143,8 +1143,7 @@ const _DayPickerGridDelegate _dayPickerGridDelegate = _DayPickerGridDelegate();
 class YearPicker extends StatefulWidget {
   /// Creates a year picker.
   ///
-  /// The [firstDate], [lastDate], [selectedDate], and [onChanged]
-  /// arguments must be non-null. The [lastDate] must be after the [firstDate].
+  /// The [lastDate] must be after the [firstDate].
   YearPicker({
     super.key,
     DateTime? currentDate,

packages/flutter/lib/src/material/card.dart

@@ -58,8 +58,7 @@ import 'theme.dart';
 class Card extends StatelessWidget {
   /// Creates a Material Design card.
   ///
-  /// The [elevation] must be null or non-negative. The [borderOnForeground]
-  /// must not be null.
+  /// The [elevation] must be null or non-negative.
   const Card({
     super.key,
     this.color,

packages/flutter/lib/src/material/card_theme.dart

@@ -110,8 +110,6 @@ class CardTheme with Diagnosticable {
 
   /// Linearly interpolate between two Card themes.
   ///
-  /// The argument `t` must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static CardTheme lerp(CardTheme? a, CardTheme? b, double t) {
     if (identical(a, b) && a != null) {

packages/flutter/lib/src/material/checkbox.dart

@@ -74,8 +74,6 @@ class Checkbox extends StatefulWidget {
   ///   can only be null if [tristate] is true.
   /// * [onChanged], which is called when the value of the checkbox should
   ///   change. It can be set to null to disable the checkbox.
-  ///
-  /// The values of [tristate] and [autofocus] must not be null.
   const Checkbox({
     super.key,
     required this.value,
@@ -391,7 +389,7 @@ class Checkbox extends StatefulWidget {
   /// this is true. This is only used when [ThemeData.useMaterial3] is set to true.
   /// {@endtemplate}
   ///
-  /// Must not be null. Defaults to false.
+  /// Defaults to false.
   final bool isError;
 
   /// {@template flutter.material.checkbox.semanticLabel}

packages/flutter/lib/src/material/checkbox_list_tile.dart

@@ -159,8 +159,6 @@ class CheckboxListTile extends StatelessWidget {
   ///   can only be null if [tristate] is true.
   /// * [onChanged], which is called when the value of the checkbox should
   ///   change. It can be set to null to disable the checkbox.
-  ///
-  /// The value of [tristate] must not be null.
   const CheckboxListTile({
     super.key,
     required this.value,

packages/flutter/lib/src/material/chip.dart

@@ -137,7 +137,7 @@ abstract interface class ChipAttributes {
 
   /// {@macro flutter.material.Material.clipBehavior}
   ///
-  /// Defaults to [Clip.none], and must not be null.
+  /// Defaults to [Clip.none].
   Clip get clipBehavior;
 
   /// {@macro flutter.widgets.Focus.focusNode}
@@ -333,7 +333,7 @@ abstract interface class SelectableChipAttributes {
   /// If [onSelected] is not null, this value will be used to determine if the
   /// select check mark will be shown or not.
   ///
-  /// Must not be null. Defaults to false.
+  /// Defaults to false.
   bool get selected;
 
   /// Called when the chip should change between selected and de-selected
@@ -447,7 +447,7 @@ abstract interface class DisabledChipAttributes {
   /// For classes which don't have this as a constructor argument, [isEnabled]
   /// returns true if their user action callback is set.
   ///
-  /// Defaults to true. Cannot be null.
+  /// Defaults to true.
   bool get isEnabled;
 
   /// The color used for the chip's background to indicate that it is not
@@ -561,7 +561,6 @@ abstract interface class TappableChipAttributes {
 class Chip extends StatelessWidget implements ChipAttributes, DeletableChipAttributes {
   /// Creates a Material Design chip.
   ///
-  /// The [label], [autofocus], and [clipBehavior] arguments must not be null.
   /// The [elevation] must be null or non-negative.
   const Chip({
     super.key,
@@ -707,10 +706,8 @@ class RawChip extends StatefulWidget
   /// The [onPressed] and [onSelected] callbacks must not both be specified at
   /// the same time.
   ///
-  /// The [label], [isEnabled], [selected], [autofocus], and [clipBehavior]
-  /// arguments must not be null. The [pressElevation] and [elevation] must be
-  /// null or non-negative. Typically, [pressElevation] is greater than
-  /// [elevation].
+  /// The [pressElevation] and [elevation] must be null or non-negative.
+  /// Typically, [pressElevation] is greater than [elevation].
   const RawChip({
     super.key,
     this.defaultProperties,

packages/flutter/lib/src/material/chip_theme.dart

@@ -42,8 +42,6 @@ import 'theme.dart';
 ///    application.
 class ChipTheme extends InheritedTheme {
   /// Applies the given theme [data] to [child].
-  ///
-  /// The [data] and [child] arguments must not be null.
   const ChipTheme({
     super.key,
     required this.data,
@@ -490,8 +488,6 @@ class ChipThemeData with Diagnosticable {
 
   /// Linearly interpolate between two chip themes.
   ///
-  /// The arguments must not be null.
-  ///
   /// {@macro dart.ui.shadow.lerp}
   static ChipThemeData? lerp(ChipThemeData? a, ChipThemeData? b, double t) {
     if (identical(a, b)) {

packages/flutter/lib/src/material/choice_chip.dart

@@ -22,8 +22,7 @@ enum _ChipVariant { flat, elevated }
 /// [ChoiceChip]s represent a single choice from a set. Choice chips contain
 /// related descriptive text or categories.
 ///
-/// Requires one of its ancestors to be a [Material] widget. The [selected] and
-/// [label] arguments must not be null.
+/// Requires one of its ancestors to be a [Material] widget.
 ///
 /// {@tool dartpad}
 /// This example shows how to create [ChoiceChip]s with [onSelected]. When the

packages/flutter/lib/src/material/data_table.dart

@@ -36,8 +36,6 @@ typedef DataColumnSortCallback = void Function(int columnIndex, bool ascending);
 @immutable
 class DataColumn {
   /// Creates the configuration for a column of a [DataTable].
-  ///
-  /// The [label] argument must not be null.
   const DataColumn({
     required this.label,
     this.tooltip,
@@ -112,8 +110,6 @@ class DataColumn {
 @immutable
 class DataRow {
   /// Creates the configuration for a row of a [DataTable].
-  ///
-  /// The [cells] argument must not be null.
   const DataRow({
     this.key,
     this.selected = false,
@@ -126,8 +122,6 @@ class DataRow {
 
   /// Creates the configuration for a row of a [DataTable], deriving
   /// the key from a row index.
-  ///
-  /// The [cells] argument must not be null.
   DataRow.byIndex({
     int? index,
     this.selected = false,
@@ -248,8 +242,7 @@ class DataCell {
   /// Creates an object to hold the data for a cell in a [DataTable].
   ///
   /// The first argument is the widget to show for the cell, typically
-  /// a [Text] or [DropdownButton] widget; this becomes the [child]
-  /// property and must not be null.
+  /// a [Text] or [DropdownButton] widget.
   ///
   /// If the cell has no data, then a [Text] widget with placeholder
   /// text should be provided instead, and then the [placeholder]
@@ -402,7 +395,7 @@ class DataTable extends StatelessWidget {
   /// The [columns] argument must be a list of as many [DataColumn]
   /// objects as the table is to have columns, ignoring the leading
   /// checkbox column if any. The [columns] argument must have a
-  /// length greater than zero and must not be null.
+  /// length greater than zero.
   ///
   /// The [rows] argument must be a list of as many [DataRow] objects
   /// as the table is to have rows, ignoring the leading heading row
@@ -676,7 +669,7 @@ class DataTable extends StatelessWidget {
   /// The data to show in each row (excluding the row that contains
   /// the column headings).
   ///
-  /// Must be non-null, but may be empty.
+  /// The list may be empty.
   final List<DataRow> rows;
 
   /// {@template flutter.material.dataTable.dividerThickness}
@@ -712,7 +705,7 @@ class DataTable extends StatelessWidget {
   ///
   /// This can be used to clip the content within the border of the [DataTable].
   ///
-  /// Defaults to [Clip.none], and must not be null.
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   // Set by the constructor to the index of the only Column that is