src/Core/Controller.php
public function getHeaders($key = null, $default = null, $deep = false)
    {
        if (is_null($key)) {
            return $this->getRequest()->headers->all();
        }
        return $this->getRequest()->headers->get($key, $default, $deep);
    }
public function getHeaders($key = null, $default = null, $deep = false)
    {
        if (is_null($key)) {
            return $this->getRequest()->headers->all();
        }
        return $this->getRequest()->headers->get($key, $default, $deep);
    }
Get http-header value by key. If $key is NULL then method returns all http-headers

@param string $key
@param mixed $default
@param boolean $deep

@return mixed