type validation adjusted

This one is related with this [issue](https://github.com/yiisoft/yii2/issues/3774) .
You can virtually turn any simple expression into a method, but that doesn't make your code better or more understandable. On the contrary, it makes your code more cryptic, because the moment you see a method call, you have to think about what it does and make need to jump to the method implementation to understand it better. Moreover, when you expose such a method, it becomes part of the class API which users may wonder how he should make use of this method or should he use it at all.

I'm not against refactoring code, but I don't consider such refactoring is a good one.