protected function decodeCustomFields(&$decoded)
    {
        // @todo This is O(namespaces * entries) and can be optimized.
        foreach ($decoded['$xmlns'] as $prefix => $namespace) {
            if (!isset($decoded['entries'])) {
                $this->decodeObject($prefix, $namespace, $decoded);
                continue;
            }

            foreach ($decoded['entries'] as &$entry) {
                $this->decodeObject($prefix, $namespace, $entry);
            }
        }
    }