added nullable annotation for IterableApi class

Author: Evan Greer

iterableapi/src/main/java/com/iterable/iterableapi/IterableApi.java

@@ -273,7 +273,7 @@ public void getEmbeddedMessages(@Nullable Long[] placementIds, @NonNull Iterable
      * @param onFailure
      */
 
-    public void getEmbeddedMessages(Long[] placementIds, @NonNull IterableHelper.SuccessHandler onSuccess, @NonNull IterableHelper.FailureHandler onFailure) {
+    public void getEmbeddedMessages(@Nullable Long[] placementIds, @NonNull IterableHelper.SuccessHandler onSuccess, @NonNull IterableHelper.FailureHandler onFailure) {
         if (!checkSDKInitialization()) {
             return;
         }