在pre - flight响应中Access-Control-Allow-Headers不允许Content-Type

我正在构建一个使用vuejs和lumen作为api的应用程序，

我的vejs应用程序在尝试验证

XMLHttpRequest无法加载http://api.dev/auth/login。请求报头字段Content-Type在pre - flight响应中不被Access-Control-Allow-Headers允许。

我有一些中间件来处理错误

class cors {
    /**
     * @var array
     */
     protected $settings = [
      'maxAge'            => 0,
      'origin'            => '*',
      'allowMethods'      => '*',
      'exposeHeaders'     => '*',
      'allowedHeaders'    => '*'
     ];
public function handle(ServerRequestInterface $request, Closure $next)
{
   //handle preflight request
    if ('OPTIONS' == $request->getMethod()) {
        $response =  new 'Illuminate'Http'Response('',"204");
        $this->setOrigin($request, $response);
        $this->setAllowHeaders($request,$response);
        return $response;
    }
}
/**
 * @param ServerRequestInterface $request
 * @param ResponseInterface $response
 */
protected function setOrigin(ServerRequestInterface $request,$response)
{
    $origin = $this->settings['origin'];
    if (is_callable($origin)) {
        $origin = call_user_func($origin,$response->withAddedHeader('Origin',$origin));
    }
    $response->headers->set('Access-Control-Allow-Origin', $origin);
}
/**
 * @param ServerRequestInterface $request
 * @param ResponseInterface $response
 */
protected function setAllowHeaders(ServerRequestInterface $request,$response)
{
    if (isset($this->settings['allowedHeaders'])) {
        $allowedHeaders = $this->settings['allowedHeaders'];
        if (is_array($allowedHeaders)) {
            $allowedHeaders = implode(", ", $allowedHeaders);
        }
    }
    else { 
        $allowedHeaders = $request->hasHeader("Access-Control-Request-Headers");
    }
    if (isset($allowedHeaders)) {
        $response->headers->set('Access-Control-Allow-Headers', $allowedHeaders);
    }
}
}

在chrome浏览器我的响应头显示

Access-Control-Allow-Headers:*
Access-Control-Allow-Origin:*
Cache-Control:no-cache
Content-Type:text/html; charset=UTF-8
Date:Mon, 10 Oct 2016 16:10:52 GMT
Server:Caddy
Status:204 No Content
X-Powered-By:PHP/7.0.10

如果我设置了通配符Access-Control-Allow-Headers为什么它不接受header?