If you want to save HTTP header fields from the synchronous response in the XI message header, chooseHTTP Header Fields (Synchronous Response) and enter the fields in the fields Field 1 to Field 6.
The fields must have the same names as the fields that are also to be sent in the HTTP response.
The technical names of the fields are HeaderFieldOne,...,HeaderFieldSix.
The attribute namespace for the adapter is http://sap.com/xi/XI/System/HTTP.
Source: SAP Help Potal