Change analysis server protocol to omit empty lists when optional.

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

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/LinkedEditGroup.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/LinkedEditGroup.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/LinkedEditGroup.java
index 002468d5c29a4a4165887efc73c97569e1d6dc0a..42f87ef0397b53b53c7bf8848965f473d9541b27 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/LinkedEditGroup.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/LinkedEditGroup.java
@@ -83,9 +83,9 @@ public class LinkedEditGroup {
   }
 
   public static LinkedEditGroup fromJson(JsonObject jsonObject) {
-    List<Position> positions = Position.fromJsonArray(jsonObject.get("positions").getAsJsonArray());
+    List<Position> positions = jsonObject.get("positions") == null ? null : Position.fromJsonArray(jsonObject.get("positions").getAsJsonArray());
     Integer length = jsonObject.get("length").getAsInt();
-    List<LinkedEditSuggestion> suggestions = LinkedEditSuggestion.fromJsonArray(jsonObject.get("suggestions").getAsJsonArray());
+    List<LinkedEditSuggestion> suggestions = jsonObject.get("suggestions") == null ? null : LinkedEditSuggestion.fromJsonArray(jsonObject.get("suggestions").getAsJsonArray());
     return new LinkedEditGroup(positions, length, suggestions);
   }
 
@@ -124,17 +124,21 @@ public class LinkedEditGroup {
 
   public JsonObject toJson() {
     JsonObject jsonObject = new JsonObject();
-    JsonArray jsonArrayPositions = new JsonArray();
-    for(Position elt : positions) {
-      jsonArrayPositions.add(elt.toJson());
+    if (positions != null) {
+      JsonArray jsonArrayPositions = new JsonArray();
+      for(Position elt : positions) {
+        jsonArrayPositions.add(elt.toJson());
+      }
+      jsonObject.add("positions", jsonArrayPositions);
     }
-    jsonObject.add("positions", jsonArrayPositions);
     jsonObject.addProperty("length", length);
-    JsonArray jsonArraySuggestions = new JsonArray();
-    for(LinkedEditSuggestion elt : suggestions) {
-      jsonArraySuggestions.add(elt.toJson());
+    if (suggestions != null) {
+      JsonArray jsonArraySuggestions = new JsonArray();
+      for(LinkedEditSuggestion elt : suggestions) {
+        jsonArraySuggestions.add(elt.toJson());
+      }
+      jsonObject.add("suggestions", jsonArraySuggestions);
     }
-    jsonObject.add("suggestions", jsonArraySuggestions);
     return jsonObject;
   }