Add fixes for two additional lints

pkg/analysis_server/lib/src/services/correction/fix.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.
 
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/src/services/correction/fix_internal.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/error/codes.dart';
@@ skipping 140 matching lines @@
   static const IMPORT_LIBRARY_SDK =
       const FixKind('IMPORT_LIBRARY_SDK', 46, "Import library '{0}'");
   static const IMPORT_LIBRARY_SHOW =
       const FixKind('IMPORT_LIBRARY_SHOW', 45, "Update library '{0}' import");
   static const INSERT_SEMICOLON =
       const FixKind('INSERT_SEMICOLON', 50, "Insert ';'");
   static const INVOKE_CONSTRUCTOR_USING_NEW = const FixKind(
       'INVOKE_CONSTRUCTOR_USING_NEW', 50, "Invoke constructor using 'new'");
   static const LINT_ADD_OVERRIDE =
       const FixKind('LINT_ADD_OVERRIDE', 50, "Add '@override' annotation");
+  static const LINT_ADD_REQUIRED =
+      const FixKind('LINT_ADD_REQUIRED', 50, "Add '@required' annotation");
   static const LINT_REMOVE_INTERPOLATION_BRACES = const FixKind(
       'LINT_REMOVE_INTERPOLATION_BRACES',
       50,
       'Remove unnecessary interpolation braces');
   static const MAKE_CLASS_ABSTRACT =
       const FixKind('MAKE_CLASS_ABSTRACT', 50, "Make class '{0}' abstract");
   static const REMOVE_DEAD_CODE =
       const FixKind('REMOVE_DEAD_CODE', 50, "Remove dead code");
   static const MAKE_FIELD_NOT_FINAL =
       const FixKind('MAKE_FIELD_NOT_FINAL', 50, "Make field '{0}' not final");
   static const REMOVE_AWAIT = const FixKind('REMOVE_AWAIT', 50, "Remove await");
+  static const REMOVE_EMPTY_ELSE =
+      const FixKind('REMOVE_EMPTY_ELSE', 50, "Remove empty else clause");
   static const REMOVE_EMPTY_STATEMENT =
       const FixKind('REMOVE_EMPTY_STATEMENT', 50, "Remove empty statement");
   static const REMOVE_INITIALIZER =
       const FixKind('REMOVE_INITIALIZER', 50, "Remove initializer");
   static const REMOVE_METHOD_DECLARATION = const FixKind(
       'REMOVE_METHOD_DECLARATION', 50, 'Remove method declaration');
   static const REMOVE_PARAMETERS_IN_GETTER_DECLARATION = const FixKind(
       'REMOVE_PARAMETERS_IN_GETTER_DECLARATION',
       50,
       "Remove parameters in getter declaration");
@@ skipping 59 matching lines @@
   @override
   final AnalysisError error;
 
   FixContextImpl(this.resourceProvider, this.analysisDriver, this.error);
 
   FixContextImpl.from(FixContext other)
       : resourceProvider = other.resourceProvider,
         analysisDriver = other.analysisDriver,
         error = other.error;
 }