src/main/java/org/eurekaclinical/scribeupext/service/GlobusOAuth20ServiceImpl.java
@Override
    public Token getAccessToken(Token requestToken, Verifier verifier) {
        OAuthRequest request
                = new ProxyOAuthRequest(this.api.getAccessTokenVerb(),
                        this.api.getAccessTokenEndpoint(), this.proxyHost, this.proxyPort);
        String userpass = this.config.getApiKey() + ":" + this.config.getApiSecret();
        String basicAuth = "Basic " + javax.xml.bind.DatatypeConverter.printBase64Binary(userpass.getBytes());
        request.addHeader("Authorization", basicAuth);
        request.addBodyParameter("grant_type", "authorization_code");
        request.addBodyParameter("code", verifier.getValue());
        request.addBodyParameter("redirect_uri", config.getCallback());
        Response response = request.send();
        String body = response.getBody();
        JsonNode json = JsonHelper.getFirstNode(body);
        if (json != null) {
            return new Token((String) JsonHelper.get(json, "access_token"), "", body);
        } else {
            return null;
        }

    }
@Override
    public Token getAccessToken(Token requestToken, Verifier verifier) {
        OAuthRequest request
                = new ProxyOAuthRequest(this.api.getAccessTokenVerb(),
                        this.api.getAccessTokenEndpoint(), this.proxyHost, this.proxyPort);
        String userpass = this.config.getApiKey() + ":" + this.config.getApiSecret();
        String basicAuth = "Basic " + javax.xml.bind.DatatypeConverter.printBase64Binary(userpass.getBytes());
        request.addHeader("Authorization", basicAuth);
        request.addBodyParameter("grant_type", "authorization_code");
        request.addBodyParameter("code", verifier.getValue());
        request.addBodyParameter("redirect_uri", config.getCallback());
        Response response = request.send();
        String body = response.getBody();
        JsonNode json = JsonHelper.getFirstNode(body);
        if (json != null) {
            return new Token((String) JsonHelper.get(json, "access_token"), "", body);
        } else {
            return null;
        }

    }
Makes the call to request an access token for an authorized user.

@param requestToken not used.
@param verifier the code query parameter that Globus included in the
redirect after the authorization call.

@return the access token.