Make RecyclerCollectionComponentSpec recyclerTouchEventHandler @nullable

Summary: TSIA

Reviewed By: adityasharat

Differential Revision: D66987656

fbshipit-source-id: 5ce7bfaa0723f5136c8c0e1c23c81a62919cc8d6

Author: Alex Madera

litho-sections-widget/src/main/java/com/facebook/litho/sections/widget/RecyclerCollectionComponentSpec.java

@@ -174,7 +174,7 @@ public class RecyclerCollectionComponentSpec {
       @Prop(optional = true, resType = ResType.DIMEN_SIZE) int topPadding,
       @Prop(optional = true, resType = ResType.DIMEN_SIZE) int bottomPadding,
       @Prop(optional = true) boolean disableAddingPadding,
-      @Prop(optional = true) EventHandler<TouchEvent> recyclerTouchEventHandler,
+      @Prop(optional = true) @Nullable EventHandler<TouchEvent> recyclerTouchEventHandler,
       @Prop(optional = true) boolean horizontalFadingEdgeEnabled,
       @Prop(optional = true) boolean verticalFadingEdgeEnabled,
       @Prop(optional = true) boolean isLeftFadingEnabled,