make helloworldservice sample yaml instantiate the right class
diff --git a/xos/tosca/samples/helloworld-chain.yaml b/xos/tosca/samples/helloworld-chain.yaml
index 9a00ddf..2e2812a 100644
--- a/xos/tosca/samples/helloworld-chain.yaml
+++ b/xos/tosca/samples/helloworld-chain.yaml
@@ -34,6 +34,7 @@
        properties:
            kind: helloworldservice_complete
            service_specific_attribute: "{\"display_message\": \"Hello World from Tosca\"}"
+           model: helloworldservice_complete.models.HelloWorldTenantComplete
        requirements:
            - provider_service:
                node: service_helloworld