src/Client/ApiClient.php
private function encodeUTF8($object)
    {
        if (\is_array($object)) {
            return array_map([$this, 'encodeUTF8'], $object);
        }

        return mb_convert_encoding((string) $object, 'UTF-8', 'auto');
    }
private function encodeUTF8($object)
    {
        if (\is_array($object)) {
            return array_map([$this, 'encodeUTF8'], $object);
        }

        return mb_convert_encoding((string) $object, 'UTF-8', 'auto');
    }
Converts any string or array of strings to UTF8.

@param mixed|mixed[] $object a String or an array

@return mixed|mixed[] UTF8-string or array