Refactored similar GraphCollection paging methods and returned nil for non-existant pages
Refactored similar GraphCollection paging methods and returned nil for non-existant pages

lucaskds/koala,supriyantomaftuh/koala,hendricius/koala,arsduo/koala,sancopanco/koala,adparlor/koala,mateusrevoredo/koala,Loke155/koala,sideci-sample/sideci-sample-koala,morgoth/koala,christer155/koala,lisa-lina/koala,chrisortman/koala,samnang/koala