Validation of `@required` params (#26182).

pkg/analyzer/lib/src/dart/element/handle.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.generated.element_handle;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 53 matching lines @@
   @override
   bool get isMixinApplication => actualElement.isMixinApplication;
 
   @override
   bool get isOrInheritsProxy => actualElement.isOrInheritsProxy;
 
   @override
   bool get isProxy => actualElement.isProxy;
 
   @override
+  bool get isRequired => actualElement.isRequired;
+
+  @override
   bool get isValidMixin => actualElement.isValidMixin;
 
   @override
   ElementKind get kind => ElementKind.CLASS;
 
   @override
   List<MethodElement> get methods => actualElement.methods;
 
   @override
   List<InterfaceType> get mixins => actualElement.mixins;
@@ skipping 271 matching lines @@
   @override
   bool get isPrivate => actualElement.isPrivate;
 
   @override
   bool get isProtected => actualElement.isProtected;
 
   @override
   bool get isPublic => actualElement.isPublic;
 
   @override
+  bool get isRequired => actualElement.isRequired;
+
+  @override
   bool get isSynthetic => actualElement.isSynthetic;
 
   @override
   LibraryElement get library =>
       getAncestor((element) => element is LibraryElement);
 
   @override
   ElementLocation get location => _location;
 
   @override
@@ skipping 718 matching lines @@
   @override
   bool get isPotentiallyMutatedInScope =>
       actualElement.isPotentiallyMutatedInScope;
 
   @override
   bool get isStatic => actualElement.isStatic;
 
   @override
   DartType get type => actualElement.type;
 }