src/Checkout/CheckoutComponentConfig.php
public function getData()
    {
        $data = array();

        foreach ($this->getComponents() as $component) {
            $orderdata = $component->getData($this->order);

            if (is_array($orderdata)) {
                $data = array_merge($data, $orderdata);
            } else {
                user_error('getData on  ' . $component->name() . ' must return an array');
            }
        }
        return $data;
    }
public function getData()
    {
        $data = array();

        foreach ($this->getComponents() as $component) {
            $orderdata = $component->getData($this->order);

            if (is_array($orderdata)) {
                $data = array_merge($data, $orderdata);
            } else {
                user_error('getData on  ' . $component->name() . ' must return an array');
            }
        }
        return $data;
    }
Get combined data

@return array map of field names to data values