I can't think of anything that is required to be connected to that lug. You need the hot, neutral and insulated EGC from the line side, the hot, neutral and EGC to the light via the cord and the #8 bonding conductor from the niche.
The niche also gets bonded to pool steel.
These days the niche is usually plastic so all you are really bonding is the speed nut that the light screws into
