// create a system contribution to hold the definitions. The contribution
// will be extended later with definitions from application contributions
systemContribution = contributionFactory.createContribution();
systemContribution.setURI("http://tuscany.apache.org/SystemContribution");
systemContribution.setLocation("http://tuscany.apache.org/SystemContribution");
ModelResolver modelResolver = new ExtensibleModelResolver(systemContribution, modelResolvers, modelFactories);
systemContribution.setModelResolver(modelResolver);
systemContribution.setUnresolved(true);
// create an artifact to represent the system defintions and
// add it to the contribution