type DelegatingAuthenticatorConfig struct {
	Anonymous bool

	// TokenAccessReviewClient is a client to do token review. It can be nil. Then every token is ignored.
	TokenAccessReviewClient authenticationclient.TokenReviewInterface

	// CacheTTL is the length of time that a token authentication answer will be cached.
	CacheTTL time.Duration

	// ClientCAFile is the CA bundle file used to authenticate client certificates
	ClientCAFile string

	APIAudiences authenticator.Audiences

	RequestHeaderConfig *RequestHeaderConfig
}

type RequestHeaderConfig struct {
	// UsernameHeaders are the headers to check (in order, case-insensitively) for an identity. The first header with a value wins.
	UsernameHeaders []string
	// GroupHeaders are the headers to check (case-insensitively) for a group names.  All values will be used.
	GroupHeaders []string
	// ExtraHeaderPrefixes are the head prefixes to check (case-insentively) for filling in
	// the user.Info.Extra.  All values of all matching headers will be added.
	ExtraHeaderPrefixes []string
	// ClientCA points to CA bundle file which is used verify the identity of the front proxy
	ClientCA string
	// AllowedClientNames is a list of common names that may be presented by the authenticating front proxy.  Empty means: accept any.
	AllowedClientNames []string
}