public void TestClearOneof()
 {
     TestOneof2.Builder builder = TestOneof2.CreateBuilder().SetFooInt(123);
     Assert.AreEqual(TestOneof2.FooOneofCase.FooInt, builder.FooCase);
     builder.ClearFoo();
     Assert.AreEqual(TestOneof2.FooOneofCase.None, builder.FooCase);
 }