Remove unnecessary cast.
Remove unnecessary cast.

ReactiveX/RxScala,TracyLu/RxScala,hermanbanken/RxScala,samuelgruetter/RxScala,joohnnie/RxScala,hermanbanken/RxScala,zhongdj/RxScala,jbripley/RxScala,zjrstar/RxScala,samuelgruetter/RxScala,jbripley/RxScala