Root Cause: The Apache CXF Framework (RA_WS 4.x) which is used as the communication layer to the service, does not support this type of WSDL.
Axis2 (RA_WS 3.x) also doesn't support rpc/encoded WSDLs.
There are plans to implement a NATIVE mode where requests and responses will bypass the CXF framework in such cases in a future version of the SOAP 4 Agent, but as of May 2017 there is no concrete date as to when this new feature will be added.
Fix Status: No Fix
Use cURL commands.