It is possible to have soapAction="" in a WSDL. Consequently the BC SOAP must support incoming message with empty string as SOAP action. It does not work currently.
[Petals.Container.Components.petals-bc-soap]-FINE 2010-10-20 15:12:19,780 Receiving a message from Axis2 engine
[Petals.Container.Components.petals-bc-soap]-FINE 2010-10-20 15:12:19,780 Processing the incoming SOAP message
[Petals.Container.Components.petals-bc-soap]-FINEST 2010-10-20 15:12:21,912 soapAction found in the incoming message :
[Petals.Container.Components.petals-bc-soap.jetty]-FINEST 2010-10-20 15:13:04,399 RESPONSE /petals/services/Talend 500