Mark string props as nullable in scrollview managers (#48520)

Summary:
Pull Request resolved: #48520

Both `ReactScrollViewHelper.parseSnapToAlignment` and `ReactScrollViewHelper.parseOverScrollMode` accept a nullable string. This is a precursor to migrating these files to Kotlin (since they're already marked as nullsafe). The prop itself is a nullable string so this should be reflected in the native types as well

Changelog: [Internal]

Reviewed By: tdn120

Differential Revision: D67911553

fbshipit-source-id: aabe55c2dc65a933b170d76b89f62f25493ab0ee

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollViewManager.java

@@ -109,7 +109,7 @@ public void setSnapToInterval(ReactHorizontalScrollView view, float snapToInterv
   }
 
   @ReactProp(name = "snapToAlignment")
-  public void setSnapToAlignment(ReactHorizontalScrollView view, String alignment) {
+  public void setSnapToAlignment(ReactHorizontalScrollView view, @Nullable String alignment) {
     view.setSnapToAlignment(ReactScrollViewHelper.parseSnapToAlignment(alignment));
   }
 
@@ -166,7 +166,7 @@ public void setSendMomentumEvents(ReactHorizontalScrollView view, boolean sendMo
    * @param scrollPerfTag
    */
   @ReactProp(name = "scrollPerfTag")
-  public void setScrollPerfTag(ReactHorizontalScrollView view, String scrollPerfTag) {
+  public void setScrollPerfTag(ReactHorizontalScrollView view, @Nullable String scrollPerfTag) {
     view.setScrollPerfTag(scrollPerfTag);
   }
 
@@ -177,7 +177,7 @@ public void setPagingEnabled(ReactHorizontalScrollView view, boolean pagingEnabl
 
   /** Controls overScroll behaviour */
   @ReactProp(name = "overScrollMode")
-  public void setOverScrollMode(ReactHorizontalScrollView view, String value) {
+  public void setOverScrollMode(ReactHorizontalScrollView view, @Nullable String value) {
     view.setOverScrollMode(ReactScrollViewHelper.parseOverScrollMode(value));
   }
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java

@@ -123,7 +123,7 @@ public void setSnapToOffsets(ReactScrollView view, @Nullable ReadableArray snapT
   }
 
   @ReactProp(name = "snapToAlignment")
-  public void setSnapToAlignment(ReactScrollView view, String alignment) {
+  public void setSnapToAlignment(ReactScrollView view, @Nullable String alignment) {
     view.setSnapToAlignment(ReactScrollViewHelper.parseSnapToAlignment(alignment));
   }
 
@@ -186,7 +186,7 @@ public void setBottomFillColor(ReactScrollView view, int color) {
 
   /** Controls overScroll behaviour */
   @ReactProp(name = "overScrollMode")
-  public void setOverScrollMode(ReactScrollView view, String value) {
+  public void setOverScrollMode(ReactScrollView view, @Nullable String value) {
     view.setOverScrollMode(ReactScrollViewHelper.parseOverScrollMode(value));
   }