Change analysis server protocol to omit empty lists when optional.

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

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/ChangeContentOverlay.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/ChangeContentOverlay.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/ChangeContentOverlay.java
index 45714b45229c960d994e64cb22cabcc9723b5e57..51c408764c41b7b00f9ab5de09caa1ba643b3003 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/ChangeContentOverlay.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/ChangeContentOverlay.java
@@ -77,7 +77,7 @@ public class ChangeContentOverlay {
 
   public static ChangeContentOverlay fromJson(JsonObject jsonObject) {
     String type = jsonObject.get("type").getAsString();
-    List<SourceEdit> edits = SourceEdit.fromJsonArray(jsonObject.get("edits").getAsJsonArray());
+    List<SourceEdit> edits = jsonObject.get("edits") == null ? null : SourceEdit.fromJsonArray(jsonObject.get("edits").getAsJsonArray());
     return new ChangeContentOverlay(type, edits);
   }
 
@@ -107,11 +107,13 @@ public class ChangeContentOverlay {
   public JsonObject toJson() {
     JsonObject jsonObject = new JsonObject();
     jsonObject.addProperty("type", type);
-    JsonArray jsonArrayEdits = new JsonArray();
-    for(SourceEdit elt : edits) {
-      jsonArrayEdits.add(elt.toJson());
+    if (edits != null) {
+      JsonArray jsonArrayEdits = new JsonArray();
+      for(SourceEdit elt : edits) {
+        jsonArrayEdits.add(elt.toJson());
+      }
+      jsonObject.add("edits", jsonArrayEdits);
     }
-    jsonObject.add("edits", jsonArrayEdits);
     return jsonObject;
   }