Add fix for missing @required params.

pkg/analysis_server/lib/src/services/correction/fix.dart

Index: pkg/analysis_server/lib/src/services/correction/fix.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/fix.dart b/pkg/analysis_server/lib/src/services/correction/fix.dart
index 124621ec5d24cf1190b01e513952164507d4ba75..db04b8ae19885ab7ebec5ef09c199a3eb0bf734a 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix.dart
@@ -123,6 +123,8 @@ class DartFixKind {
       "Add optional positional parameter");
   static const ADD_MISSING_PARAMETER_REQUIRED = const FixKind(
       'ADD_MISSING_PARAMETER_REQUIRED', 30, "Add required parameter");
+  static const ADD_MISSING_REQUIRED_ARGUMENT = const FixKind(
+      'ADD_MISSING_REQUIRED_ARGUMENT', 30, "Add required argument");
   static const ADD_NE_NULL = const FixKind('ADD_NE_NULL', 50, "Add != null");
   static const ADD_PACKAGE_DEPENDENCY = const FixKind(
       'ADD_PACKAGE_DEPENDENCY', 50, "Add dependency on package '{0}'");