如何在ColdFusion中发出curl请求？

Question

我正在尝试向Freshbooks的API发布帖子，但是，我还不能让它工作。在文档中，它们显示了如何使用Curl发出请求的示例。

请求api.freshbooks.com/auth/oauth/token：

            curl -X POST -H "Api-Version: alpha" -H "Content-Type: application/json" -d '{
            "grant_type": "authorization_code",
              "client_secret": "<insert your secret>",
              "code": "<insert your authorization code>",
              "client_id": "<insert your client id>",
              "redirect_uri": "https://localhost:3000/just_an_example"
            }' "https://api.freshbooks.com/auth/oauth/token"

我正在使用ColdFusion，这是我的方法，但我总是得到500内部服务器错误。

function getAccessToken( String code ){
    var httpService = new http();
    var body = {};
    httpService.setMethod("post");
    httpService.setUrl( getApiUrl() );
    httpService.addParam(type="header", name="Content-Type", value="application/json");
    httpService.addParam(type="header",name="Api-Version",value="alpha");

    body.grant_type = "authorization_code";
    body.client_secret = getClientSecret();
    body.code = arguments.code;
    body.client_id = getClientID();
    body.redirect_uri = "https://mywebsite.com";

    serializedStr = serializeJSON( body );
    var result = httpService.send().getPrefix();

    return result;
}

我做错了什么？