grpclb: fix unused variable lint
diff --git a/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java b/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
index 13b9521..60027b9 100644
--- a/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
+++ b/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
@@ -1399,6 +1399,7 @@
     deliverResolvedAddresses(grpclbResolutionList, grpclbResolutionAttrs);
 
     assertEquals(1, fakeOobChannels.size());
+    @SuppressWarnings("unused")
     ManagedChannel oobChannel = fakeOobChannels.poll();
 
     // First balancer RPC