Rawtype iterator fixed using <?>.

Author: Nakul Sabharwal

src/main/java/com/microsoft/graph/serializer/EnumSetSerializer.java

@@ -64,7 +64,7 @@ public static EnumSet<?> deserialize(Type type, String jsonStrToDeserialize) {
     public static JsonPrimitive serialize(EnumSet<?> src) {
         String serializedString = "";
 
-        Iterator i = src.iterator();
+        Iterator<?> i = src.iterator();
         while (i.hasNext()) {
             serializedString += i.next().toString() + ",";
         }