WDSL spec to Soap object question.

WDSL spec to Soap object question.

According to the doc, the GetPartyByGLN should have a request header element - but I can't see how to set it up in the generated code.
Does anyone know if the "Cannot unwrap" statement indicates a failure to build a complete interface?

  routerSoap = interface(IInvokable)
  ['{0665B92C-D719-C758-A143-D08E93CE967A}']

    // Cannot unwrap: 
    //     - More than one strictly out element was found
    // Headers: gepirRequestHeader:pIn, gepirResponseHeader:pOut
    function  GetPartyByGLN(const requestBody: GetPartyByGLN): gepirParty; stdcall;