Nonnull annotations for native modules (#23353)

Summary:
This adds Nonnull annotations for interfaces and classes used for native modules for Android, to improve Kotlin developer experience, but also code quality checks.

[Android] [Changed] - Nonnull annotations for native module interfaces
Pull Request resolved: https://github.com/facebook/react-native/pull/23353

Differential Revision: D14018181

Pulled By: mdvacca

fbshipit-source-id: 09a583860a6075e1d6f6df8f479369ae96497133

ReactAndroid/src/main/java/com/facebook/react/ReactPackage.java

@@ -13,6 +13,8 @@ import com.facebook.react.uimanager.UIManagerModule;
 import com.facebook.react.uimanager.ViewManager;
 import java.util.List;
 
+import javax.annotation.Nonnull;
+
 /**
  * Main interface for providing additional capabilities to the catalyst framework by couple of
  * different means:
@@ -32,10 +34,10 @@ public interface ReactPackage {
    * @param reactContext react application context that can be used to create modules
    * @return list of native modules to register with the newly created catalyst instance
    */
-  List<NativeModule> createNativeModules(ReactApplicationContext reactContext);
+  List<NativeModule> createNativeModules(@Nonnull ReactApplicationContext reactContext);
 
   /**
    * @return a list of view managers that should be registered with {@link UIManagerModule}
    */
-  List<ViewManager> createViewManagers(ReactApplicationContext reactContext);
+  List<ViewManager> createViewManagers(@Nonnull ReactApplicationContext reactContext);
 }

ReactAndroid/src/main/java/com/facebook/react/bridge/NativeModule.java

@@ -9,6 +9,8 @@ package com.facebook.react.bridge;
 
 import com.facebook.proguard.annotations.DoNotStrip;
 
+import javax.annotation.Nonnull;
+
 
 /**
  * A native module whose API can be provided to JS catalyst instances.  {@link NativeModule}s whose
@@ -28,7 +30,7 @@ public interface NativeModule {
    * @return the name of this module. This will be the name used to {@code require()} this module
    * from javascript.
    */
-  String getName();
+  @Nonnull String getName();
 
   /**
    * This is called at the end of {@link CatalystApplicationFragment#createCatalystInstance()}

ReactAndroid/src/main/java/com/facebook/react/bridge/ReactContextBaseJavaModule.java

@@ -7,6 +7,7 @@
 
 package com.facebook.react.bridge;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 import android.app.Activity;
@@ -19,7 +20,7 @@ public abstract class ReactContextBaseJavaModule extends BaseJavaModule {
 
   private final ReactApplicationContext mReactApplicationContext;
 
-  public ReactContextBaseJavaModule(ReactApplicationContext reactContext) {
+  public ReactContextBaseJavaModule(@Nonnull ReactApplicationContext reactContext) {
     mReactApplicationContext = reactContext;
   }