Remove unnecessary null checks in `flutter/{foundation,services,physics}` (#118910)

* Remove unnecessary null checks in flutter/foundation

* Remove unnecessary null checks in flutter/services

* Remove unnecessary null checks in flutter/physics

packages/flutter/lib/src/foundation/annotations.dart

@@ -39,7 +39,7 @@
 ///    class that overrides the inline documentations' own description.
 class Category {
   /// Create an annotation to provide a categorization of a class.
-  const Category(this.sections) : assert(sections != null);
+  const Category(this.sections);
 
   /// The strings the correspond to the section and subsection of the
   /// category represented by this object.
@@ -74,7 +74,7 @@ class Category {
 ///    class that overrides the inline documentations' own description.
 class DocumentationIcon {
   /// Create an annotation to provide a URL to an image describing a class.
-  const DocumentationIcon(this.url) : assert(url != null);
+  const DocumentationIcon(this.url);
 
   /// The URL to an image that represents the annotated class.
   final String url;
@@ -111,7 +111,7 @@ class DocumentationIcon {
 ///    represents the class.
 class Summary {
   /// Create an annotation to provide a short description of a class.
-  const Summary(this.text) : assert(text != null);
+  const Summary(this.text);
 
   /// The text of the summary of the annotated class.
   final String text;

packages/flutter/lib/src/foundation/assertions.dart

@@ -54,9 +54,7 @@ class PartialStackFrame {
     required this.package,
     required this.className,
     required this.method,
-  }) : assert(className != null),
-       assert(method != null),
-       assert(package != null);
+  });
 
   /// An `<asynchronous suspension>` line in a stack trace.
   static const PartialStackFrame asynchronousSuspension = PartialStackFrame(
@@ -128,8 +126,7 @@ class RepetitiveStackFrameFilter extends StackFilter {
   const RepetitiveStackFrameFilter({
     required this.frames,
     required this.replacement,
-  }) : assert(frames != null),
-       assert(replacement != null);
+  });
 
   /// The shape of this repetitive stack pattern.
   final List<PartialStackFrame> frames;
@@ -177,8 +174,7 @@ abstract class _ErrorDiagnostic extends DiagnosticsProperty<List<Object>> {
     String message, {
     DiagnosticsTreeStyle style = DiagnosticsTreeStyle.flat,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(message != null),
-       super(
+  }) : super(
          null,
          <Object>[message],
          showName: false,
@@ -217,8 +213,7 @@ abstract class _ErrorDiagnostic extends DiagnosticsProperty<List<Object>> {
     List<Object> messageParts, {
     DiagnosticsTreeStyle style = DiagnosticsTreeStyle.flat,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(messageParts != null),
-       super(
+  }) : super(
          null,
          messageParts,
          showName: false,
@@ -406,7 +401,7 @@ class FlutterErrorDetails with Diagnosticable {
     this.stackFilter,
     this.informationCollector,
     this.silent = false,
-  }) : assert(exception != null);
+  });
 
   /// Creates a copy of the error details but with the given fields replaced
   /// with new values.
@@ -1001,8 +996,6 @@ class FlutterError extends Error with DiagnosticableTreeMixin implements Asserti
   ///
   /// The default behavior for the [onError] handler is to call this function.
   static void dumpErrorToConsole(FlutterErrorDetails details, { bool forceReport = false }) {
-    assert(details != null);
-    assert(details.exception != null);
     bool isInDebugMode = false;
     assert(() {
       // In debug mode, we ignore the "silent" flag.
@@ -1182,8 +1175,6 @@ class FlutterError extends Error with DiagnosticableTreeMixin implements Asserti
   /// ```
   /// {@end-tool}
   static void reportError(FlutterErrorDetails details) {
-    assert(details != null);
-    assert(details.exception != null);
     onError?.call(details);
   }
 }

packages/flutter/lib/src/foundation/basic_types.dart

@@ -231,7 +231,7 @@ class Factory<T> {
   /// Creates a new factory.
   ///
   /// The `constructor` parameter must not be null.
-  const Factory(this.constructor) : assert(constructor != null);
+  const Factory(this.constructor);
 
   /// Creates a new object of type T.
   final ValueGetter<T> constructor;

packages/flutter/lib/src/foundation/binding.dart

@@ -327,7 +327,6 @@ abstract class BindingBase {
         ]);
       }
       try {
-        assert(instance != null);
         if (instance._debugConstructed && _debugInitializedType == null) {
           throw FlutterError.fromParts(<DiagnosticsNode>[
             ErrorSummary('Binding initialized without calling initInstances.'),
@@ -553,10 +552,8 @@ abstract class BindingBase {
   Future<void> lockEvents(Future<void> Function() callback) {
     final developer.TimelineTask timelineTask = developer.TimelineTask()..start('Lock events');
 
-    assert(callback != null);
     _lockCount += 1;
     final Future<void> future = callback();
-    assert(future != null, 'The lockEvents() callback returned null; it should return a Future<void> that completes when the lock is to expire.');
     future.whenComplete(() {
       _lockCount -= 1;
       if (!locked) {
@@ -627,8 +624,6 @@ abstract class BindingBase {
     required String name,
     required AsyncCallback callback,
   }) {
-    assert(name != null);
-    assert(callback != null);
     registerServiceExtension(
       name: name,
       callback: (Map<String, String> parameters) async {
@@ -658,9 +653,6 @@ abstract class BindingBase {
     required AsyncValueGetter<bool> getter,
     required AsyncValueSetter<bool> setter,
   }) {
-    assert(name != null);
-    assert(getter != null);
-    assert(setter != null);
     registerServiceExtension(
       name: name,
       callback: (Map<String, String> parameters) async {
@@ -692,9 +684,6 @@ abstract class BindingBase {
     required AsyncValueGetter<double> getter,
     required AsyncValueSetter<double> setter,
   }) {
-    assert(name != null);
-    assert(getter != null);
-    assert(setter != null);
     registerServiceExtension(
       name: name,
       callback: (Map<String, String> parameters) async {
@@ -754,9 +743,6 @@ abstract class BindingBase {
     required AsyncValueGetter<String> getter,
     required AsyncValueSetter<String> setter,
   }) {
-    assert(name != null);
-    assert(getter != null);
-    assert(setter != null);
     registerServiceExtension(
       name: name,
       callback: (Map<String, String> parameters) async {
@@ -825,8 +811,6 @@ abstract class BindingBase {
     required String name,
     required ServiceExtensionCallback callback,
   }) {
-    assert(name != null);
-    assert(callback != null);
     final String methodName = 'ext.flutter.$name';
     developer.registerExtension(methodName, (String method, Map<String, String> parameters) async {
       assert(method == methodName);

packages/flutter/lib/src/foundation/consolidate_response.dart

@@ -51,7 +51,6 @@ Future<Uint8List> consolidateHttpClientResponseBytes(
   bool autoUncompress = true,
   BytesReceivedCallback? onBytesReceived,
 }) {
-  assert(autoUncompress != null);
   final Completer<Uint8List> completer = Completer<Uint8List>.sync();
 
   final _OutputBuffer output = _OutputBuffer();

packages/flutter/lib/src/foundation/diagnostics.dart

@@ -253,28 +253,7 @@ class TextTreeConfiguration {
     this.beforeName = '',
     this.suffixLineOne = '',
     this.mandatoryFooter = '',
-  }) : assert(prefixLineOne != null),
-       assert(prefixOtherLines != null),
-       assert(prefixLastChildLineOne != null),
-       assert(prefixOtherLinesRootNode != null),
-       assert(linkCharacter != null),
-       assert(propertyPrefixIfChildren != null),
-       assert(propertyPrefixNoChildren != null),
-       assert(lineBreak != null),
-       assert(lineBreakProperties != null),
-       assert(afterName != null),
-       assert(afterDescriptionIfBody != null),
-       assert(afterDescription != null),
-       assert(beforeProperties != null),
-       assert(afterProperties != null),
-       assert(propertySeparator != null),
-       assert(bodyIndent != null),
-       assert(footer != null),
-       assert(showChildren != null),
-       assert(addBlankLineIfNoChildren != null),
-       assert(isNameOnOwnLine != null),
-       assert(isBlankLineBetweenPropertiesAndChildren != null),
-       childLinkSpace = ' ' * linkCharacter.length;
+  }) : childLinkSpace = ' ' * linkCharacter.length;
 
   /// Prefix to add to the first line to display a child with this style.
   final String prefixLineOne;
@@ -1113,8 +1092,7 @@ class TextTreeRenderer {
     int wrapWidth = 100,
     int wrapWidthProperties = 65,
     int maxDescendentsTruncatableNode = -1,
-  }) : assert(minLevel != null),
-       _minLevel = minLevel,
+  }) : _minLevel = minLevel,
        _wrapWidth = wrapWidth,
        _wrapWidthProperties = wrapWidthProperties,
        _maxDescendentsTruncatableNode = maxDescendentsTruncatableNode;
@@ -1218,7 +1196,7 @@ class TextTreeRenderer {
 
     List<DiagnosticsNode> children = node.getChildren();
 
-    String? description = node.toDescription(parentConfiguration: parentConfiguration);
+    String description = node.toDescription(parentConfiguration: parentConfiguration);
     if (config.beforeName.isNotEmpty) {
       builder.write(config.beforeName);
     }
@@ -1229,7 +1207,7 @@ class TextTreeRenderer {
     if (uppercaseTitle) {
       name = name?.toUpperCase();
     }
-    if (description == null || description.isEmpty) {
+    if (description.isEmpty) {
       if (node.showName && name != null) {
         builder.write(name, allowWrap: wrapName);
       }
@@ -1388,7 +1366,6 @@ class TextTreeRenderer {
 
       for (int i = 0; i < children.length; i++) {
         final DiagnosticsNode child = children[i];
-        assert(child != null);
         final TextTreeConfiguration childConfig = _childTextConfiguration(child, config)!;
         if (i == children.length - 1) {
           final String lastChildPrefixLineOne = '$prefixChildrenRaw${childConfig.prefixLastChildLineOne}';
@@ -1463,12 +1440,10 @@ abstract class DiagnosticsNode {
     this.showName = true,
     this.showSeparator = true,
     this.linePrefix,
-  }) : assert(showName != null),
-       assert(showSeparator != null),
+  }) : assert(
          // A name ending with ':' indicates that the user forgot that the ':' will
          // be automatically added for them when generating descriptions of the
          // property.
-       assert(
          name == null || !name.endsWith(':'),
          'Names of diagnostic nodes must not end with colons.\n'
          'name:\n'
@@ -1490,8 +1465,6 @@ abstract class DiagnosticsNode {
     DiagnosticLevel level = DiagnosticLevel.info,
     bool allowWrap = true,
   }) {
-    assert(style != null);
-    assert(level != null);
     return DiagnosticsProperty<void>(
       '',
       null,
@@ -1728,7 +1701,6 @@ abstract class DiagnosticsNode {
   }) {
     String result = super.toString();
     assert(style != null);
-    assert(minLevel != null);
     assert(() {
       if (_isSingleLine(style)) {
         result = toStringDeep(parentConfiguration: parentConfiguration, minLevel: minLevel);
@@ -1866,11 +1838,7 @@ class MessageProperty extends DiagnosticsProperty<void> {
     String message, {
     DiagnosticsTreeStyle style = DiagnosticsTreeStyle.singleLine,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(name != null),
-       assert(message != null),
-       assert(style != null),
-       assert(level != null),
-       super(name, null, description: message, style: style, level: level);
+  }) : super(name, null, description: message, style: style, level: level);
 }
 
 /// Property which encloses its string [value] in quotes.
@@ -1894,10 +1862,7 @@ class StringProperty extends DiagnosticsProperty<String> {
     super.ifEmpty,
     super.style,
     super.level,
-  }) : assert(showName != null),
-       assert(quoted != null),
-       assert(style != null),
-       assert(level != null);
+  });
 
   /// Whether the value is enclosed in double quotes.
   final bool quoted;
@@ -2005,9 +1970,7 @@ class DoubleProperty extends _NumProperty<double> {
     super.showName,
     super.style,
     super.level,
-  }) : assert(showName != null),
-       assert(style != null),
-       assert(level != null);
+  });
 
   /// Property with a [value] that is computed only when needed.
   ///
@@ -2024,9 +1987,7 @@ class DoubleProperty extends _NumProperty<double> {
     super.tooltip,
     super.defaultValue,
     super.level,
-  }) : assert(showName != null),
-       assert(level != null),
-       super.lazy();
+  }) : super.lazy();
 
   @override
   String numberToString() => debugFormatDouble(value);
@@ -2048,9 +2009,7 @@ class IntProperty extends _NumProperty<int> {
     super.defaultValue,
     super.style,
     super.level,
-  }) : assert(showName != null),
-       assert(level != null),
-       assert(style != null);
+  });
 
   @override
   String numberToString() => value.toString();
@@ -2075,8 +2034,7 @@ class PercentProperty extends DoubleProperty {
     super.tooltip,
     super.unit,
     super.level,
-  }) : assert(showName != null),
-       assert(level != null);
+  });
 
   @override
   String valueToString({ TextTreeConfiguration? parentConfiguration }) {
@@ -2150,9 +2108,7 @@ class FlagProperty extends DiagnosticsProperty<bool> {
     bool showName = false,
     Object? defaultValue,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(showName != null),
-       assert(level != null),
-       assert(ifTrue != null || ifFalse != null),
+  }) : assert(ifTrue != null || ifFalse != null),
        super(
          name,
          value,
@@ -2254,10 +2210,7 @@ class IterableProperty<T> extends DiagnosticsProperty<Iterable<T>> {
     super.showName,
     super.showSeparator,
     super.level,
-  }) : assert(style != null),
-       assert(showName != null),
-       assert(showSeparator != null),
-       assert(level != null);
+  });
 
   @override
   String valueToString({TextTreeConfiguration? parentConfiguration}) {
@@ -2335,7 +2288,7 @@ class EnumProperty<T> extends DiagnosticsProperty<T> {
     super.value, {
     super.defaultValue,
     super.level,
-  }) : assert(level != null);
+  });
 
   @override
   String valueToString({ TextTreeConfiguration? parentConfiguration }) {
@@ -2382,9 +2335,7 @@ class ObjectFlagProperty<T> extends DiagnosticsProperty<T> {
     super.ifNull,
     super.showName = false,
     super.level,
-  }) : assert(ifPresent != null || ifNull != null),
-       assert(showName != null),
-       assert(level != null);
+  }) : assert(ifPresent != null || ifNull != null);
 
   /// Shorthand constructor to describe whether the property has a value.
   ///
@@ -2396,9 +2347,7 @@ class ObjectFlagProperty<T> extends DiagnosticsProperty<T> {
     String super.name,
     super.value, {
     super.level,
-  }) : assert(name != null),
-       assert(level != null),
-       ifPresent = 'has $name',
+  }) : ifPresent = 'has $name',
        super(
     showName: false,
   );
@@ -2495,17 +2444,13 @@ class FlagsSummary<T> extends DiagnosticsProperty<Map<String, T?>> {
     super.showName,
     super.showSeparator,
     super.level,
-  }) : assert(value != null),
-       assert(showName != null),
-       assert(showSeparator != null),
-       assert(level != null);
+  });
 
   @override
   Map<String, T?> get value => super.value!;
 
   @override
   String valueToString({TextTreeConfiguration? parentConfiguration}) {
-    assert(value != null);
     if (!_hasNonNullEntry() && ifEmpty != null) {
       return ifEmpty!;
     }
@@ -2598,11 +2543,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
     this.allowNameWrap = true,
     DiagnosticsTreeStyle super.style = DiagnosticsTreeStyle.singleLine,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(showName != null),
-       assert(showSeparator != null),
-       assert(style != null),
-       assert(level != null),
-       _description = description,
+  }) : _description = description,
        _valueComputed = true,
        _value = value,
        _computeValue = null,
@@ -2640,12 +2581,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
     this.allowNameWrap = true,
     DiagnosticsTreeStyle super.style = DiagnosticsTreeStyle.singleLine,
     DiagnosticLevel level = DiagnosticLevel.info,
-  }) : assert(showName != null),
-       assert(showSeparator != null),
-       assert(defaultValue == kNoDefaultValue || defaultValue is T?),
-       assert(missingIfNull != null),
-       assert(style != null),
-       assert(level != null),
+  }) : assert(defaultValue == kNoDefaultValue || defaultValue is T?),
        _description = description,
        _valueComputed = false,
        _value = null,
@@ -2765,7 +2701,6 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
   ///
   /// `text` must not be null.
   String _addTooltip(String text) {
-    assert(text != null);
     return tooltip == null ? text : '$text ($tooltip)';
   }
 
@@ -2938,7 +2873,7 @@ class DiagnosticableNode<T extends Diagnosticable> extends DiagnosticsNode {
     super.name,
     required this.value,
     required super.style,
-  }) : assert(value != null);
+  });
 
   @override
   final T value;

packages/flutter/lib/src/foundation/node.dart

@@ -92,7 +92,6 @@ class AbstractNode {
   /// method, as in `super.attach(owner)`.
   @mustCallSuper
   void attach(covariant Object owner) {
-    assert(owner != null);
     assert(_owner == null);
     _owner = owner;
   }
@@ -124,7 +123,6 @@ class AbstractNode {
   @protected
   @mustCallSuper
   void adoptChild(covariant AbstractNode child) {
-    assert(child != null);
     assert(child._parent == null);
     assert(() {
       AbstractNode node = this;
@@ -147,7 +145,6 @@ class AbstractNode {
   @protected
   @mustCallSuper
   void dropChild(covariant AbstractNode child) {
-    assert(child != null);
     assert(child._parent == this);
     assert(child.attached == attached);
     child._parent = null;

packages/flutter/lib/src/foundation/serialization.dart

@@ -170,8 +170,7 @@ class WriteBuffer {
 /// The byte order used is [Endian.host] throughout.
 class ReadBuffer {
   /// Creates a [ReadBuffer] for reading from the specified [data].
-  ReadBuffer(this.data)
-    : assert(data != null);
+  ReadBuffer(this.data);
 
   /// The underlying data being read.
   final ByteData data;

packages/flutter/lib/src/foundation/stack_frame.dart

@@ -35,16 +35,7 @@ class StackFrame {
     required this.method,
     this.isConstructor = false,
     required this.source,
-  })  : assert(number != null),
-        assert(column != null),
-        assert(line != null),
-        assert(method != null),
-        assert(packageScheme != null),
-        assert(package != null),
-        assert(packagePath != null),
-        assert(className != null),
-        assert(isConstructor != null),
-        assert(source != null);
+  });
 
   /// A stack frame representing an asynchronous suspension.
   static const StackFrame asynchronousSuspension = StackFrame(
@@ -74,13 +65,11 @@ class StackFrame {
   ///
   /// This is normally useful with [StackTrace.current].
   static List<StackFrame> fromStackTrace(StackTrace stack) {
-    assert(stack != null);
     return fromStackString(stack.toString());
   }
 
   /// Parses a list of [StackFrame]s from the [StackTrace.toString] method.
   static List<StackFrame> fromStackString(String stack) {
-    assert(stack != null);
     return stack
         .trim()
         .split('\n')
@@ -181,7 +170,6 @@ class StackFrame {
 
   /// Parses a single [StackFrame] from a single line of a [StackTrace].
   static StackFrame? fromStackTraceLine(String line) {
-    assert(line != null);
     if (line == '<asynchronous suspension>') {
       return asynchronousSuspension;
     } else if (line == '...') {

packages/flutter/lib/src/physics/clamped_simulation.dart

@@ -36,8 +36,7 @@ class ClampedSimulation extends Simulation {
     this.xMax = double.infinity,
     this.dxMin = double.negativeInfinity,
     this.dxMax = double.infinity,
-  }) : assert(simulation != null),
-       assert(xMax >= xMin),
+  }) : assert(xMax >= xMin),
        assert(dxMax >= dxMin);
 
   /// The simulation being clamped. Calls to [x], [dx], and [isDone] are

packages/flutter/lib/src/physics/gravity_simulation.dart

@@ -70,11 +70,7 @@ class GravitySimulation extends Simulation {
     double distance,
     double endDistance,
     double velocity,
-  ) : assert(acceleration != null),
-      assert(distance != null),
-      assert(velocity != null),
-      assert(endDistance != null),
-      assert(endDistance >= 0),
+  ) : assert(endDistance >= 0),
       _a = acceleration,
       _x = distance,
       _v = velocity,

packages/flutter/lib/src/physics/spring_simulation.dart

@@ -153,12 +153,6 @@ abstract class _SpringSolution {
     double initialPosition,
     double initialVelocity,
   ) {
-    assert(spring != null);
-    assert(spring.mass != null);
-    assert(spring.stiffness != null);
-    assert(spring.damping != null);
-    assert(initialPosition != null);
-    assert(initialVelocity != null);
     final double cmk = spring.damping * spring.damping - 4 * spring.mass * spring.stiffness;
     if (cmk == 0.0) {
       return _CriticalSolution(spring, initialPosition, initialVelocity);

packages/flutter/lib/src/physics/utils.dart

@@ -8,7 +8,6 @@
 /// The `a` and `b` arguments may be null. A null value is only considered
 /// near-equal to another null value.
 bool nearEqual(double? a, double? b, double epsilon) {
-  assert(epsilon != null);
   assert(epsilon >= 0.0);
   if (a == null || b == null) {
     return a == b;

packages/flutter/lib/src/services/asset_bundle.dart

@@ -151,8 +151,6 @@ class NetworkAssetBundle extends AssetBundle {
   /// fetched.
   @override
   Future<T> loadStructuredData<T>(String key, Future<T> Function(String value) parser) async {
-    assert(key != null);
-    assert(parser != null);
     return parser(await loadString(key));
   }
 
@@ -196,8 +194,6 @@ abstract class CachingAssetBundle extends AssetBundle {
   /// callback synchronously.
   @override
   Future<T> loadStructuredData<T>(String key, Future<T> Function(String value) parser) {
-    assert(key != null);
-    assert(parser != null);
     if (_structuredDataCache.containsKey(key)) {
       return _structuredDataCache[key]! as Future<T>;
     }

packages/flutter/lib/src/services/autofill.dart

@@ -651,8 +651,7 @@ class AutofillConfiguration {
     this.autofillHints = const <String>[],
     this.hintText,
     required this.currentEditingValue,
-  }) : assert(uniqueIdentifier != null),
-       assert(autofillHints != null);
+  });
 
   /// An [AutofillConfiguration] that indicates the [AutofillClient] does not
   /// wish to be autofilled.
@@ -810,9 +809,7 @@ class _AutofillScopeTextInputConfiguration extends TextInputConfiguration {
   _AutofillScopeTextInputConfiguration({
     required this.allConfigurations,
     required TextInputConfiguration currentClientConfiguration,
-  }) : assert(allConfigurations != null),
-       assert(currentClientConfiguration != null),
-       super(inputType: currentClientConfiguration.inputType,
+  }) : super(inputType: currentClientConfiguration.inputType,
          obscureText: currentClientConfiguration.obscureText,
          autocorrect: currentClientConfiguration.autocorrect,
          smartDashesType: currentClientConfiguration.smartDashesType,
@@ -843,7 +840,6 @@ class _AutofillScopeTextInputConfiguration extends TextInputConfiguration {
 mixin AutofillScopeMixin implements AutofillScope {
   @override
   TextInputConnection attach(TextInputClient trigger, TextInputConfiguration configuration) {
-    assert(trigger != null);
     assert(
       !autofillClients.any((AutofillClient client) => !client.textInputConfiguration.autofillConfiguration.enabled),
       'Every client in AutofillScope.autofillClients must enable autofill',

packages/flutter/lib/src/services/message_codec.dart

@@ -34,8 +34,7 @@ abstract class MessageCodec<T> {
 class MethodCall {
   /// Creates a [MethodCall] representing the invocation of [method] with the
   /// specified [arguments].
-  const MethodCall(this.method, [this.arguments])
-    : assert(method != null);
+  const MethodCall(this.method, [this.arguments]);
 
   /// The name of the method to be called.
   final String method;
@@ -114,7 +113,7 @@ class PlatformException implements Exception {
     this.message,
     this.details,
     this.stacktrace,
-  }) : assert(code != null);
+  });
 
   /// An error code.
   final String code;

packages/flutter/lib/src/services/message_codecs.dart

@@ -195,7 +195,6 @@ class JSONMethodCodec implements MethodCodec {
 
   @override
   ByteData encodeErrorEnvelope({ required String code, String? message, Object? details}) {
-    assert(code != null);
     return const JSONMessageCodec().encodeMessage(<Object?>[code, message, details])!;
   }
 }

packages/flutter/lib/src/services/mouse_cursor.dart

@@ -104,9 +104,7 @@ abstract class MouseCursorSession {
   /// Create a session.
   ///
   /// All arguments must be non-null.
-  MouseCursorSession(this.cursor, this.device)
-    : assert(cursor != null),
-      assert(device != null);
+  MouseCursorSession(this.cursor, this.device);
 
   /// The cursor that created this session.
   final MouseCursor cursor;
@@ -215,7 +213,7 @@ abstract class MouseCursor with Diagnosticable {
   @override
   String toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) {
     final String debugDescription = this.debugDescription;
-    if (minLevel.index >= DiagnosticLevel.info.index && debugDescription != null) {
+    if (minLevel.index >= DiagnosticLevel.info.index) {
       return debugDescription;
     }
     return super.toString(minLevel: minLevel);
@@ -262,7 +260,6 @@ class _DeferringMouseCursor extends MouseCursor {
   /// Returns the first cursor that is not a [MouseCursor.defer].
   static MouseCursor? firstNonDeferred(Iterable<MouseCursor> cursors) {
     for (final MouseCursor cursor in cursors) {
-      assert(cursor != null);
       if (cursor != MouseCursor.defer) {
         return cursor;
       }
@@ -358,7 +355,7 @@ class SystemMouseCursor extends MouseCursor {
   // the supported system cursors are enumerated in [SystemMouseCursors].
   const SystemMouseCursor._({
     required this.kind,
-  }) : assert(kind != null);
+  });
 
   /// A string that identifies the kind of the cursor.
   ///

packages/flutter/lib/src/services/mouse_tracking.dart

@@ -51,7 +51,7 @@ class MouseTrackerAnnotation with Diagnosticable {
     this.onExit,
     this.cursor = MouseCursor.defer,
     this.validForMouseTracker = true,
-  }) : assert(cursor != null);
+  });
 
   /// Triggered when a mouse pointer, with or without buttons pressed, has
   /// entered the region and [validForMouseTracker] is true.

packages/flutter/lib/src/services/platform_channel.dart

@@ -163,9 +163,7 @@ class BasicMessageChannel<T> {
   /// The [name] and [codec] arguments cannot be null. The default [ServicesBinding.defaultBinaryMessenger]
   /// instance is used if [binaryMessenger] is null.
   const BasicMessageChannel(this.name, this.codec, { BinaryMessenger? binaryMessenger })
-      : assert(name != null),
-        assert(codec != null),
-        _binaryMessenger = binaryMessenger;
+      : _binaryMessenger = binaryMessenger;
 
   /// The logical channel on which communication happens, not null.
   final String name;
@@ -253,9 +251,7 @@ class MethodChannel {
   /// The [name] and [codec] arguments cannot be null. The default [ServicesBinding.defaultBinaryMessenger]
   /// instance is used if [binaryMessenger] is null.
   const MethodChannel(this.name, [this.codec = const StandardMethodCodec(), BinaryMessenger? binaryMessenger ])
-      : assert(name != null),
-        assert(codec != null),
-        _binaryMessenger = binaryMessenger;
+      : _binaryMessenger = binaryMessenger;
 
   /// The logical channel on which communication happens, not null.
   final String name;
@@ -300,7 +296,6 @@ class MethodChannel {
   /// nullable.
   @optionalTypeArgs
   Future<T?> _invokeMethod<T>(String method, { required bool missingOk, dynamic arguments }) async {
-    assert(method != null);
     final ByteData input = codec.encodeMethodCall(MethodCall(method, arguments));
     final ByteData? result =
       !kReleaseMode && debugProfilePlatformChannels ?
@@ -535,7 +530,7 @@ class MethodChannel {
   /// Any other exception results in an error envelope being sent.
   void setMethodCallHandler(Future<dynamic> Function(MethodCall call)? handler) {
     assert(
-      _binaryMessenger != null || ServicesBinding.instance != null,
+      _binaryMessenger != null || BindingBase.debugBindingType() != null,
       'Cannot set the method call handler before the binary messenger has been initialized. '
       'This happens when you call setMethodCallHandler() before the WidgetsFlutterBinding '
       'has been initialized. You can fix this by either calling WidgetsFlutterBinding.ensureInitialized() '
@@ -609,9 +604,7 @@ class EventChannel {
   /// Neither [name] nor [codec] may be null. The default [ServicesBinding.defaultBinaryMessenger]
   /// instance is used if [binaryMessenger] is null.
   const EventChannel(this.name, [this.codec = const StandardMethodCodec(), BinaryMessenger? binaryMessenger])
-      : assert(name != null),
-        assert(codec != null),
-        _binaryMessenger = binaryMessenger;
+      : _binaryMessenger = binaryMessenger;
 
   /// The logical channel on which communication happens, not null.
   final String name;

packages/flutter/lib/src/services/platform_views.dart

@@ -119,9 +119,6 @@ class PlatformViewsService {
     MessageCodec<dynamic>? creationParamsCodec,
     VoidCallback? onFocus,
   }) {
-    assert(id != null);
-    assert(viewType != null);
-    assert(layoutDirection != null);
     assert(creationParams == null || creationParamsCodec != null);
 
     final TextureAndroidViewController controller = TextureAndroidViewController._(
@@ -150,9 +147,6 @@ class PlatformViewsService {
     MessageCodec<dynamic>? creationParamsCodec,
     VoidCallback? onFocus,
   }) {
-    assert(id != null);
-    assert(viewType != null);
-    assert(layoutDirection != null);
     assert(creationParams == null || creationParamsCodec != null);
 
     final SurfaceAndroidViewController controller = SurfaceAndroidViewController._(
@@ -222,9 +216,6 @@ class PlatformViewsService {
     MessageCodec<dynamic>? creationParamsCodec,
     VoidCallback? onFocus,
   }) async {
-    assert(id != null);
-    assert(viewType != null);
-    assert(layoutDirection != null);
     assert(creationParams == null || creationParamsCodec != null);
 
     // TODO(amirh): pass layoutDirection once the system channel supports it.
@@ -258,8 +249,7 @@ class AndroidPointerProperties {
   const AndroidPointerProperties({
     required this.id,
     required this.toolType,
-  }) : assert(id != null),
-       assert(toolType != null);
+  });
 
   /// See Android's [MotionEvent.PointerProperties#id](https://developer.android.com/reference/android/view/MotionEvent.PointerProperties.html#id).
   final int id;
@@ -308,15 +298,7 @@ class AndroidPointerCoords {
     required this.touchMinor,
     required this.x,
     required this.y,
-  }) : assert(orientation != null),
-       assert(pressure != null),
-       assert(size != null),
-       assert(toolMajor != null),
-       assert(toolMinor != null),
-       assert(touchMajor != null),
-       assert(touchMinor != null),
-       assert(x != null),
-       assert(y != null);
+  });
 
   /// The orientation of the touch area and tool area in radians clockwise from vertical.
   ///
@@ -404,21 +386,7 @@ class AndroidMotionEvent {
     required this.source,
     required this.flags,
     required this.motionEventId,
-  }) : assert(downTime != null),
-       assert(eventTime != null),
-       assert(action != null),
-       assert(pointerCount != null),
-       assert(pointerProperties != null),
-       assert(pointerCoords != null),
-       assert(metaState != null),
-       assert(buttonState != null),
-       assert(xPrecision != null),
-       assert(yPrecision != null),
-       assert(deviceId != null),
-       assert(edgeFlags != null),
-       assert(source != null),
-       assert(flags != null),
-       assert(pointerProperties.length == pointerCount),
+  }) : assert(pointerProperties.length == pointerCount),
        assert(pointerCoords.length == pointerCount);
 
   /// The time (in ms) when the user originally pressed down to start a stream of position events,
@@ -532,12 +500,7 @@ class _AndroidMotionEventConverter {
       <int, AndroidPointerProperties>{};
   final Set<int> usedAndroidPointerIds = <int>{};
 
-  PointTransformer get pointTransformer => _pointTransformer;
-  late PointTransformer _pointTransformer;
-  set pointTransformer(PointTransformer transformer) {
-    assert(transformer != null);
-    _pointTransformer = transformer;
-  }
+  late PointTransformer pointTransformer;
 
   int? downTimeMillis;
 
@@ -554,7 +517,7 @@ class _AndroidMotionEventConverter {
   }
 
   void updatePointerPositions(PointerEvent event) {
-    final Offset position = _pointTransformer(event.position);
+    final Offset position = pointTransformer(event.position);
     pointerPositions[event.pointer] = AndroidPointerCoords(
       orientation: event.orientation,
       pressure: event.pressure,
@@ -691,10 +654,7 @@ abstract class AndroidViewController extends PlatformViewController {
     required TextDirection layoutDirection,
     dynamic creationParams,
     MessageCodec<dynamic>? creationParamsCodec,
-  })  : assert(viewId != null),
-        assert(viewType != null),
-        assert(layoutDirection != null),
-        assert(creationParams == null || creationParamsCodec != null),
+  })  : assert(creationParams == null || creationParamsCodec != null),
         _viewType = viewType,
         _layoutDirection = layoutDirection,
         _creationParams = creationParams == null ? null : _CreationParams(creationParams, creationParamsCodec!);
@@ -755,7 +715,6 @@ abstract class AndroidViewController extends PlatformViewController {
       <PlatformViewCreatedCallback>[];
 
   static int _getAndroidDirection(TextDirection direction) {
-    assert(direction != null);
     switch (direction) {
       case TextDirection.ltr:
         return kAndroidLayoutDirectionLtr;
@@ -874,10 +833,9 @@ abstract class AndroidViewController extends PlatformViewController {
   ///
   /// This is required to convert a [PointerEvent] to an [AndroidMotionEvent].
   /// It is typically provided by using [RenderBox.globalToLocal].
-  PointTransformer get pointTransformer => _motionEventConverter._pointTransformer;
+  PointTransformer get pointTransformer => _motionEventConverter.pointTransformer;
   set pointTransformer(PointTransformer transformer) {
-    assert(transformer != null);
-    _motionEventConverter._pointTransformer = transformer;
+    _motionEventConverter.pointTransformer = transformer;
   }
 
   /// Whether the platform view has already been created.
@@ -886,14 +844,12 @@ abstract class AndroidViewController extends PlatformViewController {
   /// Adds a callback that will get invoke after the platform view has been
   /// created.
   void addOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {
-    assert(listener != null);
     assert(_state != _AndroidViewState.disposed);
     _platformViewCreatedCallbacks.add(listener);
   }
 
   /// Removes a callback added with [addOnPlatformViewCreatedListener].
   void removeOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {
-    assert(listener != null);
     assert(_state != _AndroidViewState.disposed);
     _platformViewCreatedCallbacks.remove(listener);
   }
@@ -914,7 +870,6 @@ abstract class AndroidViewController extends PlatformViewController {
       return;
     }
 
-    assert(layoutDirection != null);
     _layoutDirection = layoutDirection;
 
     // If the view was not yet created we just update _layoutDirection and return, as the new
@@ -1361,9 +1316,7 @@ class UiKitViewController {
   UiKitViewController._(
     this.id,
     TextDirection layoutDirection,
-  ) : assert(id != null),
-      assert(layoutDirection != null),
-      _layoutDirection = layoutDirection;
+  ) : _layoutDirection = layoutDirection;
 
 
   /// The unique identifier of the iOS view controlled by this controller.
@@ -1384,7 +1337,6 @@ class UiKitViewController {
       return;
     }
 
-    assert(layoutDirection != null);
     _layoutDirection = layoutDirection;
 
     // TODO(amirh): invoke the iOS platform views channel direction method once available.

packages/flutter/lib/src/services/raw_keyboard_android.dart

@@ -42,11 +42,7 @@ class RawKeyEventDataAndroid extends RawKeyEventData {
     this.productId = 0,
     this.deviceId = 0,
     this.repeatCount = 0,
-  }) : assert(flags != null),
-       assert(codePoint != null),
-       assert(keyCode != null),
-       assert(scanCode != null),
-       assert(metaState != null);
+  });
 
   /// The current set of additional flags for this event.
   ///
@@ -227,7 +223,6 @@ class RawKeyEventDataAndroid extends RawKeyEventData {
 
   @override
   bool isModifierPressed(ModifierKey key, { KeyboardSide side = KeyboardSide.any }) {
-    assert(side != null);
     switch (key) {
       case ModifierKey.controlModifier:
         return _isLeftRightModifierPressed(side, modifierControl, modifierLeftControl, modifierRightControl);

packages/flutter/lib/src/services/raw_keyboard_fuchsia.dart

@@ -28,9 +28,7 @@ class RawKeyEventDataFuchsia extends RawKeyEventData {
     this.hidUsage = 0,
     this.codePoint = 0,
     this.modifiers = 0,
-  }) : assert(hidUsage != null),
-       assert(codePoint != null),
-       assert(modifiers != null);
+  });
 
   /// The USB HID usage.
   ///
@@ -107,7 +105,6 @@ class RawKeyEventDataFuchsia extends RawKeyEventData {
 
   @override
   bool isModifierPressed(ModifierKey key, { KeyboardSide side = KeyboardSide.any }) {
-    assert(side != null);
     switch (key) {
       case ModifierKey.controlModifier:
         return _isLeftRightModifierPressed(side, modifierControl, modifierLeftControl, modifierRightControl);

packages/flutter/lib/src/services/raw_keyboard_ios.dart

@@ -30,10 +30,7 @@ class RawKeyEventDataIos extends RawKeyEventData {
     this.charactersIgnoringModifiers = '',
     this.keyCode = 0,
     this.modifiers = 0,
-  }) : assert(characters != null),
-       assert(charactersIgnoringModifiers != null),
-       assert(keyCode != null),
-       assert(modifiers != null);
+  });
 
   /// The Unicode characters associated with a key-up or key-down event.
   ///

packages/flutter/lib/src/services/raw_keyboard_linux.dart

@@ -33,12 +33,7 @@ class RawKeyEventDataLinux extends RawKeyEventData {
     this.modifiers = 0,
     required this.isDown,
     this.specifiedLogicalKey,
-  }) : assert(scanCode != null),
-       assert(unicodeScalarValues != null),
-       assert((unicodeScalarValues & ~LogicalKeyboardKey.valueMask) == 0),
-       assert(keyCode != null),
-       assert(modifiers != null),
-       assert(keyHelper != null);
+  }) : assert((unicodeScalarValues & ~LogicalKeyboardKey.valueMask) == 0);
 
   /// A helper class that abstracts the fetching of the toolkit-specific mappings.
   ///

packages/flutter/lib/src/services/raw_keyboard_macos.dart

@@ -42,10 +42,7 @@ class RawKeyEventDataMacOs extends RawKeyEventData {
     this.keyCode = 0,
     this.modifiers = 0,
     this.specifiedLogicalKey,
-  }) : assert(characters != null),
-       assert(charactersIgnoringModifiers != null),
-       assert(keyCode != null),
-       assert(modifiers != null);
+  });
 
   /// The Unicode characters associated with a key-up or key-down event.
   ///

packages/flutter/lib/src/services/raw_keyboard_web.dart

@@ -35,8 +35,7 @@ class RawKeyEventDataWeb extends RawKeyEventData {
     this.location = 0,
     this.metaState = modifierNone,
     this.keyCode = 0,
-  })  : assert(code != null),
-        assert(metaState != null);
+  });
 
   /// The `KeyboardEvent.code` corresponding to this event.
   ///

packages/flutter/lib/src/services/raw_keyboard_windows.dart

@@ -35,10 +35,7 @@ class RawKeyEventDataWindows extends RawKeyEventData {
     this.scanCode = 0,
     this.characterCodePoint = 0,
     this.modifiers = 0,
-  }) : assert(keyCode != null),
-       assert(scanCode != null),
-       assert(characterCodePoint != null),
-       assert(modifiers != null);
+  });
 
   /// The hardware key code corresponding to this key event.
   ///

packages/flutter/lib/src/services/restoration.dart

@@ -259,7 +259,6 @@ class RestorationManager extends ChangeNotifier {
   /// called.
   @protected
   void handleRestorationUpdateFromEngine({required bool enabled, required Uint8List? data}) {
-    assert(enabled != null);
     assert(enabled || data == null);
 
     _isReplacing = _rootBucketIsValid && enabled;
@@ -297,7 +296,6 @@ class RestorationManager extends ChangeNotifier {
   /// by the data.
   @protected
   Future<void> sendToEngine(Uint8List encodedData) {
-    assert(encodedData != null);
     return SystemChannels.restoration.invokeMethod<void>(
       'put',
       encodedData,
@@ -344,7 +342,6 @@ class RestorationManager extends ChangeNotifier {
   @protected
   @visibleForTesting
   void scheduleSerializationFor(RestorationBucket bucket) {
-    assert(bucket != null);
     assert(bucket._manager == this);
     assert(!_debugDoingUpdate);
     _bucketsNeedingSerialization.add(bucket);
@@ -366,7 +363,6 @@ class RestorationManager extends ChangeNotifier {
   @protected
   @visibleForTesting
   void unscheduleSerializationFor(RestorationBucket bucket) {
-    assert(bucket != null);
     assert(bucket._manager == this);
     assert(!_debugDoingUpdate);
     _bucketsNeedingSerialization.remove(bucket);
@@ -502,8 +498,7 @@ class RestorationBucket {
   RestorationBucket.empty({
     required String restorationId,
     required Object? debugOwner,
-  }) : assert(restorationId != null),
-       _restorationId = restorationId,
+  }) : _restorationId = restorationId,
        _rawData = <String, Object?>{} {
     assert(() {
       _debugOwner = debugOwner;
@@ -537,8 +532,7 @@ class RestorationBucket {
   RestorationBucket.root({
     required RestorationManager manager,
     required Map<Object?, Object?>? rawData,
-  }) : assert(manager != null),
-       _manager = manager,
+  }) : _manager = manager,
        _rawData = rawData ?? <Object?, Object?>{},
        _restorationId = 'root' {
     assert(() {
@@ -561,9 +555,7 @@ class RestorationBucket {
     required String restorationId,
     required RestorationBucket parent,
     required Object? debugOwner,
-  }) : assert(restorationId != null),
-       assert(parent != null),
-       assert(parent._rawChildren[restorationId] != null),
+  }) : assert(parent._rawChildren[restorationId] != null),
        _manager = parent._manager,
        _parent = parent,
        _rawData = parent._rawChildren[restorationId]! as Map<Object?, Object?>,
@@ -635,7 +627,6 @@ class RestorationBucket {
   ///    restoration ID.
   P? read<P>(String restorationId) {
     assert(_debugAssertNotDisposed());
-    assert(restorationId != null);
     return _rawValues[restorationId] as P?;
   }
 
@@ -657,7 +648,6 @@ class RestorationBucket {
   ///    restoration ID.
   void write<P>(String restorationId, P value) {
     assert(_debugAssertNotDisposed());
-    assert(restorationId != null);
     assert(debugIsSerializableForRestoration(value));
     if (_rawValues[restorationId] != value || !_rawValues.containsKey(restorationId)) {
       _rawValues[restorationId] = value;
@@ -679,7 +669,6 @@ class RestorationBucket {
   ///    restoration ID.
   P? remove<P>(String restorationId) {
     assert(_debugAssertNotDisposed());
-    assert(restorationId != null);
     final bool needsUpdate = _rawValues.containsKey(restorationId);
     final P? result = _rawValues.remove(restorationId) as P?;
     if (_rawValues.isEmpty) {
@@ -701,7 +690,6 @@ class RestorationBucket {
   ///  * [remove], which removes a value from the bucket.
   bool contains(String restorationId) {
     assert(_debugAssertNotDisposed());
-    assert(restorationId != null);
     return _rawValues.containsKey(restorationId);
   }
 
@@ -737,7 +725,6 @@ class RestorationBucket {
   /// delete the information stored in it from the app's restoration data.
   RestorationBucket claimChild(String restorationId, {required Object? debugOwner}) {
     assert(_debugAssertNotDisposed());
-    assert(restorationId != null);
     // There are three cases to consider:
     // 1. Claiming an ID that has already been claimed.
     // 2. Claiming an ID that doesn't yet exist in [_rawChildren].
@@ -787,7 +774,6 @@ class RestorationBucket {
   /// No-op if the provided bucket is already a child of this bucket.
   void adoptChild(RestorationBucket child) {
     assert(_debugAssertNotDisposed());
-    assert(child != null);
     if (child._parent != this) {
       child._parent?._removeChildData(child);
       child._parent = this;
@@ -801,7 +787,6 @@ class RestorationBucket {
   }
 
   void _dropChild(RestorationBucket child) {
-    assert(child != null);
     assert(child._parent == this);
     _removeChildData(child);
     child._parent = null;
@@ -876,7 +861,6 @@ class RestorationBucket {
   }
 
   void _removeChildData(RestorationBucket child) {
-    assert(child != null);
     assert(child._parent == this);
     if (_claimedChildren.remove(child.restorationId) == child) {
       _rawChildren.remove(child.restorationId);
@@ -901,7 +885,6 @@ class RestorationBucket {
   }
 
   void _addChildData(RestorationBucket child) {
-    assert(child != null);
     assert(child._parent == this);
     if (_claimedChildren.containsKey(child.restorationId)) {
       // Delay addition until the end of the frame in the hopes that the current
@@ -944,7 +927,6 @@ class RestorationBucket {
   /// another ID, or has moved it to a new parent via [adoptChild].
   void rename(String newRestorationId) {
     assert(_debugAssertNotDisposed());
-    assert(newRestorationId != null);
     if (newRestorationId == restorationId) {
       return;
     }

packages/flutter/lib/src/services/spell_check.dart

@@ -27,9 +27,7 @@ class SuggestionSpan {
   ///
   /// The [range] and replacement [suggestions] must all not
   /// be null.
-  const SuggestionSpan(this.range, this.suggestions)
-      : assert(range != null),
-        assert(suggestions != null);
+  const SuggestionSpan(this.range, this.suggestions);
 
   /// The misspelled range of text.
   final TextRange range;
@@ -58,9 +56,7 @@ class SuggestionSpan {
 @immutable
 class SpellCheckResults {
   /// Creates results based off those received by spell checking some text input.
-  const SpellCheckResults(this.spellCheckedText, this.suggestionSpans)
-      : assert(spellCheckedText != null),
-        assert(suggestionSpans != null);
+  const SpellCheckResults(this.spellCheckedText, this.suggestionSpans);
 
   /// The text that the [suggestionSpans] correspond to.
   final String spellCheckedText;
@@ -170,8 +166,6 @@ class DefaultSpellCheckService implements SpellCheckService {
   @override
   Future<List<SuggestionSpan>?> fetchSpellCheckSuggestions(
       Locale locale, String text) async {
-    assert(locale != null);
-    assert(text != null);
 
     final List<dynamic> rawResults;
     final String languageTag = locale.toLanguageTag();

packages/flutter/lib/src/services/system_chrome.dart

@@ -577,7 +577,6 @@ class SystemChrome {
   ///
   ///  * [AnnotatedRegion], the widget used to place data into the layer tree.
   static void setSystemUIOverlayStyle(SystemUiOverlayStyle style) {
-    assert(style != null);
     if (_pendingStyle != null) {
       // The microtask has already been queued; just update the pending value.
       _pendingStyle = style;

packages/flutter/lib/src/services/text_editing_delta.dart

@@ -64,9 +64,7 @@ abstract class TextEditingDelta with Diagnosticable {
     required this.oldText,
     required this.selection,
     required this.composing,
-  }) : assert(oldText != null),
-       assert(selection != null),
-       assert(composing != null);
+  });
 
   /// Creates an instance of this class from a JSON object by inferring the
   /// type of delta based on values sent from the engine.

packages/flutter/lib/src/services/text_formatter.dart

@@ -121,8 +121,7 @@ typedef TextInputFormatFunction = TextEditingValue Function(
 
 /// Wiring for [TextInputFormatter.withFunction].
 class _SimpleTextInputFormatter extends TextInputFormatter {
-  _SimpleTextInputFormatter(this.formatFunction)
-    : assert(formatFunction != null);
+  _SimpleTextInputFormatter(this.formatFunction);
 
   final TextInputFormatFunction formatFunction;
 
@@ -271,9 +270,7 @@ class FilteringTextInputFormatter extends TextInputFormatter {
     this.filterPattern, {
     required this.allow,
     this.replacementString = '',
-  }) : assert(filterPattern != null),
-       assert(allow != null),
-       assert(replacementString != null);
+  });
 
   /// Creates a formatter that only allows characters matching a pattern.
   ///

packages/flutter/lib/src/services/text_input.dart

@@ -478,17 +478,8 @@ class TextInputConfiguration {
     this.autofillConfiguration = AutofillConfiguration.disabled,
     this.enableIMEPersonalizedLearning = true,
     this.enableDeltaModel = false,
-  }) : assert(inputType != null),
-       assert(obscureText != null),
-       smartDashesType = smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
-       smartQuotesType = smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled),
-       assert(autocorrect != null),
-       assert(enableSuggestions != null),
-       assert(keyboardAppearance != null),
-       assert(inputAction != null),
-       assert(textCapitalization != null),
-       assert(enableIMEPersonalizedLearning != null),
-       assert(enableDeltaModel != null);
+  }) : smartDashesType = smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
+       smartQuotesType = smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled);
 
   /// The type of information for which to optimize the text input control.
   final TextInputType inputType;
@@ -746,8 +737,7 @@ class RawFloatingCursorPoint {
   RawFloatingCursorPoint({
     this.offset,
     required this.state,
-  }) : assert(state != null),
-       assert(state != FloatingCursorDragState.Update || offset != null);
+  }) : assert(state != FloatingCursorDragState.Update || offset != null);
 
   /// The raw position of the floating cursor as determined by the iOS sdk.
   final Offset? offset;
@@ -773,13 +763,7 @@ class TextEditingValue {
     this.text = '',
     this.selection = const TextSelection.collapsed(offset: -1),
     this.composing = TextRange.empty,
-  }) : assert(text != null),
-       // The constructor does not verify that `selection` and `composing` are
-       // valid ranges within `text`, and is unable to do so due to limitation
-       // of const constructors. Some checks are performed by assertion in
-       // other occasions. See `_textRangeIsValid`.
-       assert(selection != null),
-       assert(composing != null);
+  });
 
   /// Creates an instance of this class from a JSON object.
   factory TextEditingValue.fromJSON(Map<String, dynamic> encoded) {
@@ -1300,8 +1284,7 @@ mixin DeltaTextInputClient implements TextInputClient {
 ///    the system's text input using a [TextInputConnection].
 class TextInputConnection {
   TextInputConnection._(this._client)
-      : assert(_client != null),
-        _id = _nextId++;
+      : _id = _nextId++;
 
   Size? _cachedSize;
   Matrix4? _cachedTransform;
@@ -1318,7 +1301,6 @@ class TextInputConnection {
   /// application code will likely break text input for the application.
   @visibleForTesting
   static void debugResetId({int to = 1}) {
-    assert(to != null);
     assert(() {
       _nextId = to;
       return true;
@@ -1395,7 +1377,6 @@ class TextInputConnection {
   /// This information is used for positioning the IME candidates menu on each
   /// platform.
   void setComposingRect(Rect rect) {
-    assert(rect != null);
     if (rect == _cachedRect) {
       return;
     }
@@ -1407,7 +1388,6 @@ class TextInputConnection {
   /// Sends the coordinates of caret rect. This is used on macOS for positioning
   /// the accent selection menu.
   void setCaretRect(Rect rect) {
-    assert(rect != null);
     if (rect == _cachedCaretRect) {
       return;
     }
@@ -1515,7 +1495,6 @@ FloatingCursorDragState _toTextCursorAction(String state) {
 }
 
 RawFloatingCursorPoint _toTextPoint(FloatingCursorDragState state, Map<String, dynamic> encoded) {
-  assert(state != null, 'You must provide a state to set a new editing point.');
   assert(encoded['X'] != null, 'You must provide a value for the horizontal location of the floating cursor.');
   assert(encoded['Y'] != null, 'You must provide a value for the vertical location of the floating cursor.');
   final Offset offset = state == FloatingCursorDragState.Update
@@ -1699,8 +1678,6 @@ class TextInput {
   /// should call [TextInputConnection.close] on the returned
   /// [TextInputConnection].
   static TextInputConnection attach(TextInputClient client, TextInputConfiguration configuration) {
-    assert(client != null);
-    assert(configuration != null);
     final TextInputConnection connection = TextInputConnection._(client);
     _instance._attach(connection, configuration);
     return connection;
@@ -1710,9 +1687,6 @@ class TextInput {
   // by [attach] and by [_handleTextInputInvocation] for the
   // `TextInputClient.requestExistingInputState` method.
   void _attach(TextInputConnection connection, TextInputConfiguration configuration) {
-    assert(connection != null);
-    assert(connection._client != null);
-    assert(configuration != null);
     assert(_debugEnsureInputActionWorksOnPlatform(configuration.inputAction));
     _currentConnection = connection;
     _currentConfiguration = configuration;
@@ -1806,7 +1780,6 @@ class TextInput {
     // The requestExistingInputState request needs to be handled regardless of
     // the client ID, as long as we have a _currentConnection.
     if (method == 'TextInputClient.requestExistingInputState') {
-      assert(_currentConnection!._client != null);
       _attach(_currentConnection!, _currentConfiguration);
       final TextEditingValue? editingValue = _currentConnection!._client.currentTextEditingValue;
       if (editingValue != null) {
@@ -1820,7 +1793,6 @@ class TextInput {
     // The updateEditingStateWithTag request (autofill) can come up even to a
     // text field that doesn't have a connection.
     if (method == 'TextInputClient.updateEditingStateWithTag') {
-      assert(_currentConnection!._client != null);
       final TextInputClient client = _currentConnection!._client;
       final AutofillScope? scope = client.currentAutofillScope;
       final Map<String, dynamic> editingValue = args[1] as Map<String, dynamic>;
@@ -1951,14 +1923,12 @@ class TextInput {
   }
 
   void _updateConfig(TextInputConfiguration configuration) {
-    assert(configuration != null);
     for (final TextInputControl control in _inputControls) {
       control.updateConfig(configuration);
     }
   }
 
   void _setEditingState(TextEditingValue value) {
-    assert(value != null);
     for (final TextInputControl control in _inputControls) {
       control.setEditingState(value);
     }
@@ -2094,7 +2064,6 @@ class TextInput {
   /// * [AutofillGroup.onDisposeAction], a configurable action that runs when a
   ///   topmost [AutofillGroup] is getting disposed.
   static void finishAutofillContext({ bool shouldSave = true }) {
-    assert(shouldSave != null);
     for (final TextInputControl control in TextInput._instance._inputControls) {
       control.finishAutofillContext(shouldSave: shouldSave);
     }