diff --git a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApi.java b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApi.java
index bd970fccc8..116a23eef7 100644
--- a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApi.java
+++ b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApi.java
@@ -44,12 +44,12 @@ public interface NetworkApi {
     * Returns the list of all networks currently defined in Quantum for the current tenant. The list provides the unique
     * identifier of each network configured for the tenant.
     */
-   Set<Reference> listReferences();
+   Set<? extends Reference> listReferences();
 
    /**
     * Returns all networks currently defined in Quantum for the current tenant.
     */
-   Set<Network> list();
+   Set<? extends Network> list();
 
    /**
     * Returns the specific network.
diff --git a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkAsyncApi.java b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkAsyncApi.java
index 44a8feabe9..ffb680528c 100644
--- a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkAsyncApi.java
+++ b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/NetworkAsyncApi.java
@@ -64,7 +64,7 @@ public interface NetworkAsyncApi {
    @GET
    @SelectJson("networks")
    @ExceptionParser(ReturnEmptySetOnNotFoundOr404.class)
-   ListenableFuture<Set<Reference>> listReferences();
+   ListenableFuture<? extends Set<? extends Reference>> listReferences();
 
    /**
     * @see NetworkApi#list
@@ -73,7 +73,7 @@ public interface NetworkAsyncApi {
    @SelectJson("networks")
    @Path("/detail")
    @ExceptionParser(ReturnEmptySetOnNotFoundOr404.class)
-   ListenableFuture<Set<Network>> list();
+   ListenableFuture<? extends Set<? extends Network>> list();
 
    /**
     * @see NetworkApi#get
@@ -82,7 +82,7 @@ public interface NetworkAsyncApi {
    @SelectJson("network")
    @Path("/{id}")
    @ExceptionParser(ReturnNullOnNotFoundOr404.class)
-   ListenableFuture<Network> get(@PathParam("id") String id);
+   ListenableFuture<? extends Network> get(@PathParam("id") String id);
 
    /**
     * @see NetworkApi#getDetails
@@ -91,7 +91,7 @@ public interface NetworkAsyncApi {
    @SelectJson("network")
    @Path("/{id}/detail")
    @ExceptionParser(ReturnNullOnNotFoundOr404.class)
-   ListenableFuture<NetworkDetails> getDetails(@PathParam("id") String id);
+   ListenableFuture<? extends NetworkDetails> getDetails(@PathParam("id") String id);
 
    /**
     * @see NetworkApi#create
@@ -100,7 +100,7 @@ public interface NetworkAsyncApi {
    @SelectJson("network")
    @Produces(MediaType.APPLICATION_JSON)
    @WrapWith("network")
-   ListenableFuture<Reference> create(@PayloadParam("name") String name);
+   ListenableFuture<? extends Reference> create(@PayloadParam("name") String name);
 
    /**
     * @see NetworkApi#rename
diff --git a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortApi.java b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortApi.java
index 5acc661add..5f65506caf 100644
--- a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortApi.java
+++ b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortApi.java
@@ -44,12 +44,12 @@ public interface PortApi {
    /**
     * Returns the list of all ports currently defined in Quantum for the requested network
     */
-   Set<Reference> listReferences();
+   Set<? extends Reference> listReferences();
 
    /**
     * Returns the set of ports currently defined in Quantum for the requested network.
     */
-   Set<Port> list();
+   Set<? extends Port> list();
 
    /**
     * Returns a specific port.
diff --git a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortAsyncApi.java b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortAsyncApi.java
index c0c1e44b3c..a11b474b1d 100644
--- a/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortAsyncApi.java
+++ b/labs/openstack-quantum/src/main/java/org/jclouds/openstack/quantum/v1_0/features/PortAsyncApi.java
@@ -64,7 +64,7 @@ public interface PortAsyncApi {
    @GET
    @SelectJson("ports")
    @ExceptionParser(ReturnEmptySetOnNotFoundOr404.class)
-   ListenableFuture<Set<Reference>> listReferences();
+   ListenableFuture<? extends Set<? extends Reference>> listReferences();
 
    /**
     * @see PortApi#list
@@ -73,7 +73,7 @@ public interface PortAsyncApi {
    @SelectJson("ports")
    @Path("/detail")
    @ExceptionParser(ReturnEmptySetOnNotFoundOr404.class)
-   ListenableFuture<Set<Port>> list();
+   ListenableFuture<? extends Set<? extends Port>> list();
 
    /**
     * @see PortApi#get
@@ -82,7 +82,7 @@ public interface PortAsyncApi {
    @SelectJson("port")
    @Path("/{id}")
    @ExceptionParser(ReturnNullOnNotFoundOr404.class)
-   ListenableFuture<Port> get(@PathParam("id") String id);
+   ListenableFuture<? extends Port> get(@PathParam("id") String id);
 
    /**
     * @see PortApi#getDetails
@@ -92,14 +92,14 @@ public interface PortAsyncApi {
    @Consumes(MediaType.APPLICATION_JSON)
    @Path("/{id}/detail")
    @ExceptionParser(ReturnNullOnNotFoundOr404.class)
-   ListenableFuture<PortDetails> getDetails(@PathParam("id") String id);
+   ListenableFuture<? extends PortDetails> getDetails(@PathParam("id") String id);
 
    /**
     * @see PortApi#create()
     */
    @POST
    @SelectJson("port")
-   ListenableFuture<Reference> create();
+   ListenableFuture<? extends Reference> create();
 
    /**
     * @see PortApi#create(org.jclouds.openstack.quantum.v1_0.domain.Port.State) 
@@ -131,7 +131,7 @@ public interface PortAsyncApi {
    @SelectJson("attachment")
    @Path("/{id}/attachment")
    @ExceptionParser(ReturnNullOnNotFoundOr404.class)   
-   ListenableFuture<Attachment> showAttachment(@PathParam("id") String portId);
+   ListenableFuture<? extends Attachment> showAttachment(@PathParam("id") String portId);
 
    /**
     * @see PortApi#plugAttachment
diff --git a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiExpectTest.java b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiExpectTest.java
index da8b08717e..bf23dfb041 100644
--- a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiExpectTest.java
+++ b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiExpectTest.java
@@ -55,7 +55,7 @@ public void testListReferencesReturns2xx() {
             HttpResponse.builder().statusCode(200).payload(payloadFromResourceWithContentType("/list_network_refs.json", APPLICATION_JSON)).build())
             .getNetworkApiForRegion("region-a.geo-1");
       
-      Set<Reference> nets = api.listReferences();
+      Set<? extends Reference> nets = api.listReferences();
       assertEquals(nets, listOfNetworkRefs());
    }
 
@@ -76,7 +76,7 @@ public void testListReturns2xx() {
             HttpResponse.builder().statusCode(200).payload(payloadFromResourceWithContentType("/list_networks.json", APPLICATION_JSON)).build())
             .getNetworkApiForRegion("region-a.geo-1");
 
-      Set<Network> nets = api.list();
+      Set<? extends Network> nets = api.list();
       assertEquals(nets, listOfNetworks());
    }
 
diff --git a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiLiveTest.java b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiLiveTest.java
index a0060be346..5add5bf041 100644
--- a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiLiveTest.java
+++ b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/NetworkApiLiveTest.java
@@ -42,8 +42,8 @@ public class NetworkApiLiveTest extends BaseQuantumApiLiveTest {
 
    public void testListNetworks() {
       for (String regionId : quantumContext.getApi().getConfiguredRegions()) {
-         Set<Reference> ids = quantumContext.getApi().getNetworkApiForRegion(regionId).listReferences();
-         Set<Network> networks = quantumContext.getApi().getNetworkApiForRegion(regionId).list();
+         Set<? extends Reference> ids = quantumContext.getApi().getNetworkApiForRegion(regionId).listReferences();
+         Set<? extends Network> networks = quantumContext.getApi().getNetworkApiForRegion(regionId).list();
          assertNotNull(ids);
          assertEquals(ids.size(), networks.size());
          for (Network network : networks) {
diff --git a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiExpectTest.java b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiExpectTest.java
index 640b6ed431..02a61a1c3d 100644
--- a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiExpectTest.java
+++ b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiExpectTest.java
@@ -56,7 +56,7 @@ public void testListReferencesReturns2xx() {
             HttpResponse.builder().statusCode(200).payload(payloadFromStringWithContentType("{\"ports\": [{\"id\": \"a6058a59-fa8c-46cc-bac8-08904e6ff0a5\"}]}", APPLICATION_JSON)).build())
             .getPortApiForRegionAndNetwork("region-a.geo-1", "1a104cf5-cb18-4d35-9407-2fd2646d9d0b");
 
-      Set<Reference> nets = api.listReferences();
+      Set<? extends Reference> nets = api.listReferences();
       assertEquals(nets, ImmutableSet.of(Reference.builder().id("a6058a59-fa8c-46cc-bac8-08904e6ff0a5").build()));
    }
 
@@ -77,7 +77,7 @@ public void testListReturns2xx() {
             HttpResponse.builder().statusCode(200).payload(payloadFromStringWithContentType("{\"ports\": [{\"state\": \"DOWN\", \"id\": \"814ae4bb-33d9-425f-8ee2-13a5c90b1465\"}]}", APPLICATION_JSON)).build())
             .getPortApiForRegionAndNetwork("region-a.geo-1", "1a104cf5-cb18-4d35-9407-2fd2646d9d0b");
 
-      Set<Port> nets = api.list();
+      Set<? extends Port> nets = api.list();
       assertEquals(nets, ImmutableSet.of(Port.builder().state(Port.State.DOWN).id("814ae4bb-33d9-425f-8ee2-13a5c90b1465").build()));
    }
 
diff --git a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiLiveTest.java b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiLiveTest.java
index 68c92a6d83..b179061fe0 100644
--- a/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiLiveTest.java
+++ b/labs/openstack-quantum/src/test/java/org/jclouds/openstack/quantum/v1_0/features/PortApiLiveTest.java
@@ -46,11 +46,11 @@ public class PortApiLiveTest extends BaseQuantumApiLiveTest {
    public void testListPorts() {
       for (String regionId : quantumContext.getApi().getConfiguredRegions()) {
          NetworkApi netApi = quantumContext.getApi().getNetworkApiForRegion(regionId);
-         Set<Reference> nets = netApi.listReferences();
+         Set<? extends Reference> nets = netApi.listReferences();
          for(Reference net : nets) {
             PortApi portApi = quantumContext.getApi().getPortApiForRegionAndNetwork(regionId, net.getId());
-            Set<Reference> portRefs = portApi.listReferences();
-            Set<Port> ports = portApi.list();
+            Set<? extends Reference> portRefs = portApi.listReferences();
+            Set<? extends Port> ports = portApi.list();
             
             assertEquals(portRefs.size(), ports.size());
             for (Port port : ports) {