You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: doorkeeper_oauth.rb
    path of file: ./repos/openproject/lib_static/open_project/authentication/strategies/warden
    
    the code of the file until where you have to start completion: require 'doorkeeper/grape/authorization_decorat
    
          def find_credential_app_user(app_id)
            ::Doorkeeper::Application
              .where(id: app_id)
              .where.not(client_credentials_user_id: nil)
              .pluck(:client_credentials_user_id)
              .first
          end