adds additional track purchase function

Author: Evan Greer

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

@@ -1029,6 +1029,20 @@ public void trackPurchase(double total, @NonNull List<CommerceItem> items) {
         trackPurchase(total, items, null, null);
     }
 
+    /**
+     * Tracks a purchase.
+     * @param total total purchase amount
+     * @param items list of purchased items
+     * @param dataFields a `JSONObject` containing any additional information to save along with the event
+     */
+    public void trackPurchase(double total, @NonNull List<CommerceItem> items, @Nullable JSONObject dataFields) {
+        if (!checkSDKInitialization()) {
+            return;
+        }
+
+        apiClient.trackPurchase(total, items, dataFields, null);
+    }
+
     /**
      * Tracks a purchase.
      * @param total total purchase amount