Add nullable annotation to handleImagePicked method uri parameter

app/src/main/java/fr/free/nrw/commons/contributions/ContributionController.java

@@ -7,6 +7,7 @@
 import android.net.Uri;
 import android.os.Bundle;
 import android.provider.MediaStore;
+import android.support.annotation.Nullable;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentActivity;
 import android.support.v4.content.FileProvider;
@@ -91,7 +92,7 @@ public void startGalleryPick() {
         fragment.startActivityForResult(pickImageIntent, SELECT_FROM_GALLERY);
     }
 
-    public void handleImagePicked(int requestCode, Uri uri, boolean isDirectUpload, String wikiDataEntityId) {
+    public void handleImagePicked(int requestCode, @Nullable Uri uri, boolean isDirectUpload, String wikiDataEntityId) {
         FragmentActivity activity = fragment.getActivity();
         Timber.d("handleImagePicked() called with onActivityResult()");
         Intent shareIntent = new Intent(activity, ShareActivity.class);