Fix covariance generics type 
Fix covariance generics type 
Rowandjj/Lightweight-Stream-API,fabioCollini/Lightweight-Stream-API,awendland/Lightweight-Stream-API,tsdl2013/Lightweight-Stream-API,RyanTech/Lightweight-Stream-API,aNNiMON/Lightweight-Stream-API,msoftware/Lightweight-Stream-API