SolvedAlamofire validate() "eats" response data

[Request]: <NSMutableURLRequest: 0x10040ddd0> { URL: https://platform.devtest.ringcentral.com/restapi/oauth/token }
[Response]: <NSHTTPURLResponse: 0x10025f980> { URL: https://platform.devtest.ringcentral.com/restapi/oauth/token } { status code: 400, headers {
    Connection = "keep-alive";
    "Content-Language" = en;
    "Content-Length" = 83;
    "Content-Type" = "application/json;charset=UTF-8";
    Date = "Fri, 26 Aug 2016 15:03:27 GMT";
    RCRequestId = "3e87d7de-6b9e-11e6-a8f4-005056bb594d";
    RoutingKey = SJC11P01PAS01;
    Server = "nginx/1.8.0";
    "Www-Authenticate" = "Basic realm=\"RingCentral REST API\"";
    "X-LoadMetric" = 4;
} }
[Data]: 83 bytes
[Result]: SUCCESS: {
  "error" : "invalid_request",
  "error_description" : "Unsupported grant type"
}
[Timeline]: Timeline: { "Request Start Time": 493916605.929, "Initial Response Time": 493916607.145, "Request Completed Time": 493916607.146, "Serialization Completed Time": 493916607.146, "Latency": 1.217 secs, "Request Duration": 1.217 secs, "Serialization Duration": 0.000 secs, "Total Duration": 1.217 secs }

[Request]: <NSMutableURLRequest: 0x10040a5b0> { URL: https://platform.devtest.ringcentral.com/restapi/oauth/token }
[Response]: <NSHTTPURLResponse: 0x100365bd0> { URL: https://platform.devtest.ringcentral.com/restapi/oauth/token } { status code: 400, headers {
    Connection = "keep-alive";
    "Content-Language" = en;
    "Content-Length" = 83;
    "Content-Type" = "application/json;charset=UTF-8";
    Date = "Fri, 26 Aug 2016 15:05:49 GMT";
    RCRequestId = "9328183a-6b9e-11e6-b36a-005056bb26b9";
    RoutingKey = SJC11P01PAS01;
    Server = "nginx/1.8.0";
    "Www-Authenticate" = "Basic realm=\"RingCentral REST API\"";
    "X-LoadMetric" = 4;
} }
[Data]: 83 bytes
[Result]: FAILURE: Error Domain=com.alamofire.error Code=-6003 "Response status code was unacceptable: 400" UserInfo={StatusCode=400, NSLocalizedFailureReason=Response status code was unacceptable: 400}
[Timeline]: Timeline: { "Request Start Time": 493916746.708, "Initial Response Time": 493916749.121, "Request Completed Time": 493916749.121, "Serialization Completed Time": 493916749.122, "Latency": 2.413 secs, "Request Duration": 2.413 secs, "Serialization Duration": 0.001 secs, "Total Duration": 2.414 secs }

{
  "error" : "invalid_request",
  "error_description" : "Unsupported grant type"
}

if let responseData = response.data {
    let responseDataString = NSString(data: responseData, encoding:NSUTF8StringEncoding)
    print(responseDataString)
}