protected function validateRootFilter(): void
    {
        $rootFilter = $this->getArrayValue($this->joryArray, ['flt', 'filter']);

        // It is not required to add a filter, the absence of a filter just means: don't apply a filter.
        // An empty array also counts as no filter.
        // And if no filter is present, there can be no errors; so return.
        if ($rootFilter === null || count($rootFilter) === 0) {
            return;
        }

        // There is a filter, loop through all filters
        $this->validateFilter($rootFilter, $this->address.'filter');
    }