public function getSources(string $fieldType, $sources, string $indexFrom, string $indexTo)
    {
        $mappedSources = $sources;
        if (is_array($sources)) {
            $mappedSources = [];
            $sources = array_filter($sources);
            foreach ($sources as $source) {
                $mappedSources[] = $this->getSource($fieldType, $source, $indexFrom, $indexTo);
            }
        }

        return $mappedSources;
    }