code: func (m *manager) Current() *tls.Certificate {
  	m.certAccessLock.RLock()
  	defer m.certAccessLock.RUnlock()
  	if m.cert != nil && m.cert.Leaf != nil && time.Now().After(m.cert.Leaf.NotAfter) {
  		klog.V(2).Infof("Current certificate is expired.")
  		return nil
  	}
  	return m.cert
  }
docs: // Current returns the currently selected certificate from the certificate
  // manager. This can be nil if the manager was initialized without a
  // certificate and has not yet received one from the
  // CertificateSigningRequestClient, or if the current cert has expired.