Shimano A070 rear derailleur

doughosie1

Hello Everyone, I'm new to this site and I'm in desperate need of your help. I don't know how but the small spring, the one that has an eyelet at one end and the other end has a hook, has come off my rear derailleur and i have no idea where each end is supposed to fasten to. I'm new to road bikes and cycling in general and I've been using my bike on a trainer since it's been so cold out. Could anyone please help me with this? Thanks