Block on the future in device-role CLI command

Change-Id: I20e3784a39eb79b8cfb50a60a5b27185c98c5163
diff --git a/cli/src/main/java/org/onosproject/cli/net/DeviceRoleCommand.java b/cli/src/main/java/org/onosproject/cli/net/DeviceRoleCommand.java
index 46ddd98..17fc87a 100644
--- a/cli/src/main/java/org/onosproject/cli/net/DeviceRoleCommand.java
+++ b/cli/src/main/java/org/onosproject/cli/net/DeviceRoleCommand.java
@@ -22,6 +22,8 @@
 import org.onosproject.mastership.MastershipAdminService;
 import org.onosproject.net.MastershipRole;
 
+import com.google.common.util.concurrent.Futures;
+
 import static org.onosproject.net.DeviceId.deviceId;
 
 /**
@@ -47,7 +49,7 @@
     protected void execute() {
         MastershipAdminService service = get(MastershipAdminService.class);
         MastershipRole mastershipRole = MastershipRole.valueOf(role.toUpperCase());
-        service.setRole(new NodeId(node), deviceId(uri), mastershipRole);
+        Futures.getUnchecked(service.setRole(new NodeId(node), deviceId(uri), mastershipRole));
     }
 
 }