Bug in SWA (Soap with attachment) with Content-Id header
I found bug in SWA support in SOAP UI. When sending multipart mime request, attachment Content-Id header should contain also name of attachment from WSDL e.g. Content-ID: <content=sample.txt> instead of Content-ID: <sample.txt>.
Workaround is to set ContentID column to value content=sample.txt like in screenshot: