Remove unused helper class previously used by extend(). (#4745)
Remove unused helper class previously used by extend(). (#4745)


hzysoft/RxJava,weikipeng/RxJava,davidmoten/RxJava,hzysoft/RxJava,weikipeng/RxJava,davidmoten/RxJava,weikipeng/RxJava,hzysoft/RxJava,davidmoten/RxJava