Add support to receive null payload in events

Reviewed By: shergin

Differential Revision: D8439118

fbshipit-source-id: a45da18765d58f6e32d34e2e57f3a6a64daccf71

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -639,6 +639,9 @@ public class FabricUIManager implements UIManager, JSHandler {
         TAG,
         "Dispatching event for target: " + eventTarget);
     }
+    if (params == null) {
+      params = new WritableNativeMap();
+    }
     mBinding.dispatchEventToTarget(mJSContext.get(), mEventHandlerPointer, eventTarget, name, (WritableNativeMap) params);
   }