Update SharedPreferencesFlipperPlugin param that received null value …

…to Nullable

Summary:
Runtime plugin showed null key passed into onSharedPreferenceChanged. Required buck dependency to allow nullable annotation.

## Context
We are in the process of making the entire codebase Nullsafe. This diff relies on a runtime codemod to track when null is passed into a parameter that is not marked as Nullable in java. Based on runtime data, we can be 100% certain that this parameter needs to be Nullable

Reviewed By: jocelynluizzi13

Differential Revision: D60586640

fbshipit-source-id: 1740e3bbec73186c908ed2cc31f52c0cd5fc12d9

android/src/main/java/com/facebook/flipper/plugins/sharedpreferences/SharedPreferencesFlipperPlugin.java

@@ -25,6 +25,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.Nullable;
 
 public class SharedPreferencesFlipperPlugin implements FlipperPlugin {
 
@@ -36,7 +37,8 @@ public class SharedPreferencesFlipperPlugin implements FlipperPlugin {
       onSharedPreferenceChangeListener =
           new SharedPreferences.OnSharedPreferenceChangeListener() {
             @Override
-            public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
+            public void onSharedPreferenceChanged(
+                SharedPreferences sharedPreferences, @Nullable String key) {
               if (mConnection == null) {
                 return;
               }