Restructure things to fit upcoming diff

java/csharp/Facebook.CSSLayout/NullableAttribute.cs

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System;
+
+namespace Facebook.CSSLayout
+{
+    /**
+    * This is here to preserve the @nullable attribute of the original Java API.
+    */
+
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.ReturnValue | AttributeTargets.Parameter)]
+    sealed class NullableAttribute : Attribute
+    {
+    }
+}