class Doorkeeper::OAuth::Client::Credentials

def self.from_request(request, *credentials_methods)
  credentials_methods.inject(nil) do |credentials, method|
    method = self.method(method) if method.is_a?(Symbol)
    credentials = Credentials.new *method.call(request)
    break credentials unless credentials.blank?
  end
end

def blank?
  uid.blank? || secret.blank?
end