Make RefactoringProblem.location optional.

editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java
index 88dd815314ecc968f4f776f3855f3aaf86354815..b960ec3f329be507b3ebd2c20718dce5199d8456 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/RefactoringProblem.java
@@ -49,7 +49,9 @@ public class RefactoringProblem {
   private final String message;
 
   /**
-   * The location of the problem being represented.
+   * The location of the problem being represented. This field is omitted unless there is a specific
+   * location associated with the problem (such as a location where an element being renamed will be
+   * shadowed).
    */
   private final Location location;
 
@@ -75,7 +77,9 @@ public class RefactoringProblem {
   }
 
   /**
-   * The location of the problem being represented.
+   * The location of the problem being represented. This field is omitted unless there is a specific
+   * location associated with the problem (such as a location where an element being renamed will be
+   * shadowed).
    */
   public Location getLocation() {
     return location;
@@ -99,7 +103,9 @@ public class RefactoringProblem {
     JsonObject jsonObject = new JsonObject();
     jsonObject.addProperty("severity", severity);
     jsonObject.addProperty("message", message);
-    jsonObject.add("location", location.toJson());
+    if (location != null) {
+      jsonObject.add("location", location.toJson());
+    }
     return jsonObject;
   }