Change analysis server protocol to omit empty lists when optional.

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

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/SourceChange.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/SourceChange.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/SourceChange.java
index cc021607f9d684996164dd746653478cd88a6956..639edd5dfb3344b3c82c14bd42be9f498176138c 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/SourceChange.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/generated/types/SourceChange.java
@@ -87,8 +87,8 @@ public class SourceChange {
 
   public static SourceChange fromJson(JsonObject jsonObject) {
     String message = jsonObject.get("message").getAsString();
-    List<SourceFileEdit> edits = SourceFileEdit.fromJsonArray(jsonObject.get("edits").getAsJsonArray());
-    List<LinkedEditGroup> linkedEditGroups = LinkedEditGroup.fromJsonArray(jsonObject.get("linkedEditGroups").getAsJsonArray());
+    List<SourceFileEdit> edits = jsonObject.get("edits") == null ? null : SourceFileEdit.fromJsonArray(jsonObject.get("edits").getAsJsonArray());
+    List<LinkedEditGroup> linkedEditGroups = jsonObject.get("linkedEditGroups") == null ? null : LinkedEditGroup.fromJsonArray(jsonObject.get("linkedEditGroups").getAsJsonArray());
     Position selection = jsonObject.get("selection") == null ? null : Position.fromJson(jsonObject.get("selection").getAsJsonObject());
     return new SourceChange(message, edits, linkedEditGroups, selection);
   }
@@ -136,16 +136,20 @@ public class SourceChange {
   public JsonObject toJson() {
     JsonObject jsonObject = new JsonObject();
     jsonObject.addProperty("message", message);
-    JsonArray jsonArrayEdits = new JsonArray();
-    for(SourceFileEdit elt : edits) {
-      jsonArrayEdits.add(elt.toJson());
+    if (edits != null) {
+      JsonArray jsonArrayEdits = new JsonArray();
+      for(SourceFileEdit elt : edits) {
+        jsonArrayEdits.add(elt.toJson());
+      }
+      jsonObject.add("edits", jsonArrayEdits);
     }
-    jsonObject.add("edits", jsonArrayEdits);
-    JsonArray jsonArrayLinkedEditGroups = new JsonArray();
-    for(LinkedEditGroup elt : linkedEditGroups) {
-      jsonArrayLinkedEditGroups.add(elt.toJson());
+    if (linkedEditGroups != null) {
+      JsonArray jsonArrayLinkedEditGroups = new JsonArray();
+      for(LinkedEditGroup elt : linkedEditGroups) {
+        jsonArrayLinkedEditGroups.add(elt.toJson());
+      }
+      jsonObject.add("linkedEditGroups", jsonArrayLinkedEditGroups);
     }
-    jsonObject.add("linkedEditGroups", jsonArrayLinkedEditGroups);
     if (selection != null) {
       jsonObject.add("selection", selection.toJson());
     }