eZ\Publish\Core\FieldType\Page\Type::validateFieldSettings PHP Method

    public function validateFieldSettings($fieldSettings)
    {
        $validationErrors = array();
        foreach ($fieldSettings as $name => $value) {
            if (isset($this->settingsSchema[$name])) {
                switch ($name) {
                    case 'defaultLayout':
                        if ($value !== '' && !in_array($value, $this->pageService->getAvailableZoneLayouts())) {
                            $validationErrors[] = new ValidationError("Layout '{$value}' for setting '%setting%' is not available", null, array('%setting%' => $name), "[{$name}]");
                        }
                        break;
                }
            } else {
                $validationErrors[] = new ValidationError("Setting '%setting%' is unknown", null, array('%setting%' => $name), "[{$name}]");
            }
        }
        return $validationErrors;
    }