Empty Actions when mocking Java Web Service

I get the
“System.InvalidOperationException: The operations methodX and methodY have the same action ().  Every operation must have a unique action value”, when trying to mock a Java Web Service with Rhino Mocks in CSharp.

The WSDL-file that was downloaded from the Java Web Service declared an empty soap action for each exported operation.
For example:

<operation name="aMethod">
  <soap:operation soapAction="" /> 
  <input>
   <soap:body use="literal" /> 
  </input>
  <output>
   <soap:body use="literal" /> 
  </output>
  <fault name="MyWebServiceException">
   <soap:fault name="MyWebServiceException" use="literal" /> 
  </fault>
</operation>

WCF uses the action to dispatch an incoming message to the correct method, see Action Property. Each method must have a unique action value.

I solved it by downloading the WSDL-file and remove all soap action declarations:

<soap:operation soapAction="" />

I ran the svcutil.exe on the changed WSDL-file.
WCF then creates unique action values in the service interface file, and the service can be mocked (as I described in Mocking WCF service).