Webiny\Component\Entity\EntityDataExtractor::buildNestedKeys PHP Method

    private function buildNestedKeys($fields)
    {
        $keys = [];
        foreach ($fields as $f => $nestedFields) {
            if (is_array($nestedFields)) {
                $nestedKeys = $this->buildNestedKeys($nestedFields);
                foreach ($nestedKeys as $k) {
                    $keys[] = $f . '.' . $k;
                }
            } else {
                $keys[] = $f;
            }
        }
        return $keys;
    }