core-bundle/src/HttpKernel/ModelArgumentResolver.php
public function supports(Request $request, ArgumentMetadata $argument): bool
    {
        if (!$this->scopeMatcher->isContaoRequest($request)) {
            return false;
        }

        $this->framework->initialize();

        if (!is_a($argument->getType(), Model::class, true)) {
            return false;
        }

        if (!$argument->isNullable() && null === $this->fetchModel($request, $argument)) {
            return false;
        }

        return true;
    }
public function supports(Request $request, ArgumentMetadata $argument): bool
    {
        if (!$this->scopeMatcher->isContaoRequest($request)) {
            return false;
        }

        $this->framework->initialize();

        if (!is_a($argument->getType(), Model::class, true)) {
            return false;
        }

        if (!$argument->isNullable() && null === $this->fetchModel($request, $argument)) {
            return false;
        }

        return true;
    }
{@inheritdoc}