kubernetes/staging/src/k8s.io/apiserver/pkg/authentication/group/group_adder.go

type GroupAdder …

// NewGroupAdder wraps a request authenticator, and adds the specified groups to the returned user when authentication succeeds
func NewGroupAdder(auth authenticator.Request, groups []string) authenticator.Request { … }

func (g *GroupAdder) AuthenticateRequest(req *http.Request) (*authenticator.Response, bool, error) { … }