private function extractPrefixKeyValueData($prefix)
    {
        $result = null;
        
        // If it has key-value data, as evidenced by the raw prefix string
        // being a JSON object (not JSON array), use it.
        if (substr($prefix, 0, 1) === '{') {
            if ($this->isJsonString($prefix)) {
                $result = Json::decode($prefix);
            }
        }
        
        return $result;
    }