Fix the bug in dataUtils for typeToken

Author: MingquanLiu

api/src/main/java/edu/cmu/chimps/messageontap_api/DataUtils.java

@@ -66,7 +66,7 @@ public static String SimpleObjectToJson(Object object, String typeKey) {
         Gson gson = new Gson();
         switch (typeKey) {
             case Globals.TYPE_TRIGGER:
-                Type type = new TypeToken<List<Trigger>>() {
+                Type type = new TypeToken<Trigger>() {
                 }.getType();
                 return gson.toJson(object, type);
             default:
@@ -78,7 +78,7 @@ public static Object JsonToSimpleObject(String json, String typeKey) {
         Gson gson = new Gson();
         switch (typeKey) {
             case Globals.TYPE_TRIGGER:
-                Type type = new TypeToken<List<Trigger>>() {
+                Type type = new TypeToken<Trigger>() {
                 }.getType();
                 return gson.fromJson(json, type);
             default: