1.递归定义泛型1.1原始情况-问题由来当我们定义了如下的关系的类时：abstractclassAbstractBuilder{privatevarid:Int?=nullopenfunsetId(id:Int):AbstractBuilder{this.id=idreturnthis}}openclassMyBuilder1:AbstractBuilder(){privatevarname:String?=nullopenfunsetName(name:String):MyBuilder1{this.name=namereturnthis}}classMyBuilder2:MyBuilder
