code: func (j *JWKClient) GetSecret(r *http.Request) (interface{}, error) {
  	token, err := j.extractor.Extract(r)
  	if err != nil {
  		return nil, err
  	}
  
  	if len(token.Headers) < 1 {
  		return nil, ErrNoJWTHeaders
  	}
  
  	header := token.Headers[0]
  
  	return j.GetKey(header.KeyID)
  }
docs: // GetSecret implements the GetSecret method of the SecretProvider interface.