I`m writing gmod lua script which just should check constraints for prop spawned by user (like ropes), but it always return false even if I spawn constrained props

if SERVER then
    hook.Add("PlayerSpawnedProp", "PrintConstraintsCount", function(player, entity)
        print(constraint.HasConstraints(entity))
    end)
end

I expect the normal acting, but it dont seem to do it, the code is so small that i even cant say many things about it!