add missing __nullable attributes
add missing __nullable attributes

houweilei/AFNetworking,adozenlines/AFNetworking,p4checo/AFNetworking,RbBtSn0w/AFNetworking,purdyk/AFNetworking,yunzhongyoulong/AFNetworking,Juraldinio/AFNetworking,zhang-yawei/AFNetworking,houweilei/AFNetworking,opentable/AFNetworking,adozenlines/AFNetworking,AFNetworking/AFNetworking,yunzhongyoulong/AFNetworking,Kjuly/AFNetworking,DevSonw/AFNetworking,yuewenyan/AFNetworking,FelixYin66/AFNetworking,AFNetworking/AFNetworking,DevSonw/AFNetworking,rocklive/AFNetworking,wymsee/AFNetworking,Farteen/AFNetworking,Kjuly/AFNetworking,wymsee/AFNetworking,SecuraSeal/AFNetworking,nonoBruce/AFNetworking,ewanmellor/AFNetworking,kiurentu/AFNetworking,matteonovelli/AFNetworking,knutigro/AFNetworking,E-B-Smith/AFNetworking,sunkehappy/AFNetworking,iKorich/AFNetworking,0xced/AFNetworking,yuewenyan/AFNetworking,maximmalygin/AFNetworking,kiurentu/AFNetworking,Farteen/AFNetworking,wprice/AFNetworking,rocklive/AFNetworking,AFNetworking/AFNetworking,smule/AFNetworking,nonoBruce/AFNetworking,ewanmellor/AFNetworking,Automatic/AFNetworking,Yincongxiao/AFNetworking,nonoBruce/AFNetworking,Juraldinio/AFNetworking,Fitbit/AFNetworking,SecuraSeal/AFNetworking,mhpavl/AFNetworking,smule/AFNetworking,Kjuly/AFNetworking,E-B-Smith/AFNetworking,Yincongxiao/AFNetworking,renaudbuisine/MF_AFNetworking,E-B-Smith/AFNetworking,guogh/AFNetworking,knutigro/AFNetworking,Automatic/AFNetworking,0xced/AFNetworking,michal-olszewski/AFNetworking-CustomCallbacks,RbBtSn0w/AFNetworking,wprice/AFNetworking,michal-olszewski/AFNetworking-CustomCallbacks,maximmalygin/AFNetworking,zhang-yawei/AFNetworking,wangxiaoxiang/AFNetworking,Fitbit/AFNetworking,purdyk/AFNetworking,guogh/AFNetworking,opentable/AFNetworking,p4checo/AFNetworking,matteonovelli/AFNetworking,opentable/AFNetworking,renaudbuisine/MF_AFNetworking,mhpavl/AFNetworking