Hi João,
Thanks for your input. I've tried sending all values in the same line, and the response on outsystems was the same. The monitoring on service center returns:
400 Bad Request
at ssGoogleServicesOAuth2.CcGoogleApis.ActionAccessTokenGet(HeContext heContext, ICcGoogleApisCallbacks _callbacks, String inParamcode, String inParamclient_id, String inParamclient_secret, String inParamredirect_uri, String inParamgrant_type, STAccessTokenResponseStructure& outParamResponse)
Is supposed to encode the code send in the request? To send "4%2AAAA" instead of "4/AAAA"?