Hello Suresh,

You will need to keep nesting further and further into the User. It will look very confusing very quickly, but should be 

gs.getUser().getUserByID(gs.getUser().getUserByID(gs.getUser().getManagerID()).getManagerID()).getManagerID()

Where you will be adding 

gs.getUser().getUserByID

inside of the getUserByID.

I hope this helps explain it!

If this solved your problem, please mark as correct or helpful.

Thank you,

Cody Smith