Need to review this... but it will fix some tests that started failin…

…g after code handling changes.

sdk/client/api_client.go

@@ -129,23 +129,30 @@ func (c *APIClient) callAPI(request *http.Request) (*http.Response, error) {
 
 func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err error) {
 	if strings.Contains(contentType, "application/xml") {
-		if err = xml.Unmarshal(b, v); err != nil {
-			return err
+		if len(b) > 0 {
+			if err = xml.Unmarshal(b, v); err != nil {
+				return err
+			}
 		}
 		return nil
 	} else if strings.Contains(contentType, "application/json") {
-		if err = json.Unmarshal(b, v); err != nil {
-			return err
+		if len(b) > 0 {
+			if err = json.Unmarshal(b, v); err != nil {
+				return err
+			}
 		}
 		return nil
 	} else if strings.Contains(contentType, "text/plain") {
-		rv := reflect.ValueOf(v)
-		if rv.IsNil() {
-			return errors.New("undefined response type")
+		if len(b) == 0 {
+			rv := reflect.ValueOf(v)
+			if rv.IsNil() {
+				return errors.New("undefined response type")
+			}
+			rv.Elem().SetString(string(b))
 		}
-		rv.Elem().SetString(string(b))
 		return nil
 	}
+
 	return errors.New("undefined response type")
 }