Update UPGRADE-2.3.md to account for #9388

ureimers · fabpot · commit 8a7397425a11 · 2014-01-06T17:31:17.000+01:00
diff --git a/UPGRADE-2.3.md b/UPGRADE-2.3.md
@@ -170,6 +170,32 @@ Form
    $form = $builder->getForm();
    ```
 
+ * Previously, when the "data" option of a field was set to `null` and the
+   containing form was mapped to an object, the field would receive the data
+   from the object as default value. This functionality was unintended and fixed
+   to use `null` as default value in Symfony 2.3.
+
+   In cases where you made use of the previous behavior, you should now remove
+   the "data" option altogether.
+
+   Before:
+
+   ```
+   $builder->add('field', 'text', array(
+      'data' => $defaultData ?: null,
+   ));
+   ```
+
+   After:
+
+   ```
+   $options = array();
+   if ($defaultData) {
+       $options['data'] = $defaultData;
+   }
+   $builder->add('field', 'text', $options);
+   ```
+
 PropertyAccess
 --------------
 
