EI and APIm: Response payload is wrapped inside binary element

Question

1.1 - API Manager 2.1.0 If I sent a POST request through a simple mediation (pass through) when the binary relay was enabled, the response payload generated by ESB has been wrapped inside a binary element as follows..

HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: POST
Access-Control-Allow-Headers: authorization,Access-Control-Allow-Origin,Content-Type,SOAPAction
Content-Type: text/xml; charset=UTF-8
Date: Tue, 16 Jan 2018 14:53:00 GMT
Transfer-Encoding: chunked
Connection: close

<?xml version='1.0' encoding='UTF-8'?><soapenv:Envelope     xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><ns:binary xmlns:ns="http://ws.apache.org/commons/ns/payload">DCAAAAApACkAAAJxdXVpZDo3MTRDNkM0MC00NT.......</ns:binary></soapenv:Body></soapenv:Envelope>

In ESB 5.0.0 and API manager 2.0.0 all works well.