core/app/models/spree/payment_source.rb
module Spree
class PaymentSource < Spree::Base
include Spree::Metadata
belongs_to :payment_method, class_name: 'Spree::PaymentMethod'
belongs_to :user, class_name: 'Spree::User', optional: true
validates_uniqueness_of :gateway_payment_profile_id, scope: :type
end
end