Pimcore\Controller\Action\Admin\Element::getVersionsAction PHP Method

    public function getVersionsAction()
    {
        $id = intval($this->getParam("id"));
        $type = $this->getParam("controller");
        $allowedTypes = ["asset", "document", "object"];
        if ($id && in_array($type, $allowedTypes)) {
            $element = Model\Element\Service::getElementById($type, $id);
            if ($element) {
                if ($element->isAllowed("versions")) {
                    $schedule = $element->getScheduledTasks();
                    $schedules = [];
                    foreach ($schedule as $task) {
                        if ($task->getActive()) {
                            $schedules[$task->getVersion()] = $task->getDate();
                        }
                    }
                    $versions = $element->getVersions();
                    $versions = Model\Element\Service::getSafeVersionInfo($versions);
                    foreach ($versions as &$version) {
                        $version["scheduled"] = null;
                        if (array_key_exists($version["id"], $schedules)) {
                            $version["scheduled"] = $schedules[$version["id"]];
                        }
                    }
                    $this->_helper->json(["versions" => $versions]);
                } else {
                    throw new \Exception("Permission denied, " . $type . " id [" . $id . "]");
                }
            } else {
                throw new \Exception($type . " with id [" . $id . "] doesn't exist");
            }
        }
    }