grant.rb in rack-oauth2-1.3.1

- old
+ new

@@ -30,6 +30,7 @@
 require 'rack/oauth2/client/grant/authorization_code'
 require 'rack/oauth2/client/grant/password'
 require 'rack/oauth2/client/grant/client_credentials'
 require 'rack/oauth2/client/grant/refresh_token'
 require 'rack/oauth2/client/grant/jwt_bearer'
-require 'rack/oauth2/client/grant/saml2_bearer'
+require 'rack/oauth2/client/grant/saml2_bearer'
+require 'rack/oauth2/client/grant/token_exchange'
\ No newline at end of file