PI 7.11 process SOAP message with Attachments failed

Hello,

we have a scenario where the sender (3rd-Party) start a sync call via PI to a receiver (SAP BW system).

The receiver send a response with attachment. SAP processed the message successfully but sender could not processed message because the SOAP header do not have the attribut Content-Transfer-Encoding.

with this attribut I could tell the sender that the attachments are more then 7bit.

How to can I set this attribut into the SOAP header in the SAP PI?

Or have someone an other idee?

Thanks and regards

Martin