code: func RegisterCredentialProvider(name string, provider DockerConfigProvider) {
  	providersMutex.Lock()
  	defer providersMutex.Unlock()
  	_, found := providers[name]
  	if found {
  		glog.Fatalf("Credential provider %q was registered twice", name)
  	}
  	glog.V(1).Infof("Registered credential provider %q", name)
  	providers[name] = provider
  }
docs: // RegisterCredentialProvider is called by provider implementations on
  // initialization to register themselves, like so:
  //   func init() {
  //    	RegisterCredentialProvider("name", &myProvider{...})
  //   }