src/Kernel.php
public function containerIsCacheable(): bool
    {
        $result = true; // container is cacheable by default

        if ($this->container->hasParameter('container.cache')) {
            $result = (bool)$this->container->getParameter('container.cache');
        }

        return $result;
    }
public function containerIsCacheable(): bool
    {
        $result = true; // container is cacheable by default

        if ($this->container->hasParameter('container.cache')) {
            $result = (bool)$this->container->getParameter('container.cache');
        }

        return $result;
    }
Returns true, if the container.cache parameter does not exist or is false

@return bool