Change encoding in AMQ Classic 6.1.8 REST Connection

[trxg19]

Hi,
I am using ActiveMQ Classic in version 6.1.8 and connect via. REST API to the AMQ Broker. When retrieving messages from a queue, the message is encoded using ISO-8859-1 (Latin).

Is there a way to change this? I've already tried patching the jetty.xml file, but that didn't work. Right now, I'm having an issue where, for example, Cyrillic messages are being transmitted as ???? due to the incorrect encoding.

Even a request with the Accept header set to Accept: application/xml;charset=UTF-8 does not work. The response is always
Content-Type: text/plain;charset=iso-8859-1

Thanks and kind regards,
trxg19