facebook android sdk 4.0 , way to unregister callback from LoginManager -

i using facebook sdk 4.0 inmy android app. have activity functionality post message facebook ( not main activity of app ) doing following login facebook , post message

facebooksdk.sdkinitialize(this.getapplicationcontext()); callbackmanager = callbackmanager.factory.create(); loginmanager.getinstance().registercallback(callbackmanager,       new facebookcallback<loginresult>() {                 @override                 public void onsuccess(loginresult loginresult) {                     //login successfull, post message.                 }      }); 

questions is, how unregister callback loginmanager ? didnt find method in loginmanager so.

any reason why sdk designed in such way doesnt provide option unregister ?

problem is, if activity gets destroyed , recreated ( say, due device rotation) , loginmanager have reference previous activity instance not right.

i unregister in ondestory of activity.

thanks,

the loginmanager not hold reference callback, callback manager does. long keep callback manager 1-1 activity, callback garbage collected fine.