MethodReturnValueHandler implementations should support null return values from endpoints [SWS-867]

[gregturn]

Phil McCarley opened SWS-867 and commented

Here is an example Endpoint...

@Endpoint
@Address("urn:schemas-xmlsoap-org:ws:2005:04:discovery")
public class WsDiscovery {
    
    private static final String ENDPOINT_REFERENCE = "uuid:f7a32a18-5205-46f1-b296-e0f6ac9de7ed";

    @Action(value = "http://schemas.xmlsoap.org/ws/2005/04/discovery/Resolve", output = "http://schemas.xmlsoap.org/ws/2005/04/discovery/ResolveMatches")
    public @ResponsePayload JAXBElement<ResolveMatchesType> handleResolve(@RequestPayload JAXBElement<ResolveType> element) {
        if (ENDPOINT_REFERENCE.equals(element.getValue().getEndpointReference().getAddress())) {
            
            return new ObjectFactory().createResolveMatches(new ResolveMatchesType());
        }
        
        return null;
    }
}

In the case where we the ENDPOINT_REFERENCE doesn't match, we don't want to send a response at all, and so the method returns 'null'. However, in all but the AbstractPayloadSourceMethodProcessor implementations, either a NullPointerException or IllegalArgumentException (from the Assert.notNull) will be thrown.

I believe handling null return values by suppressing the sending of a response is the most consistent approach, given that this is what Spring MVC does.

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Affects: 2.1.4

Referenced from: commits 06ff649

[gregturn]

Arjen Poutsma commented

Fixed!