Fix incorrect input verification check in ClusterMetadata

Change-Id: I921ae8a8ba8c35bd91f27d2d1d985096f023c211
diff --git a/core/api/src/main/java/org/onosproject/cluster/ClusterMetadata.java b/core/api/src/main/java/org/onosproject/cluster/ClusterMetadata.java
index a2681e0..f0334aa 100644
--- a/core/api/src/main/java/org/onosproject/cluster/ClusterMetadata.java
+++ b/core/api/src/main/java/org/onosproject/cluster/ClusterMetadata.java
@@ -174,8 +174,8 @@
          */
         private void verifyMetadata() {
             verifyNotNull(metadata.getName(), "Cluster name must be specified");
-            verify(CollectionUtils.isEmpty(metadata.getNodes()), "Cluster nodes must be specified");
-            verify(CollectionUtils.isEmpty(metadata.getPartitions()), "Cluster partitions must be specified");
+            verify(CollectionUtils.isNotEmpty(metadata.getNodes()), "Cluster nodes must be specified");
+            verify(CollectionUtils.isNotEmpty(metadata.getPartitions()), "Cluster partitions must be specified");
 
             // verify that partitions are constituted from valid cluster nodes.
             boolean validPartitions = Collections2.transform(metadata.getNodes(), ControllerNode::id)
@@ -186,4 +186,4 @@
             verify(validPartitions, "Partition locations must be valid cluster nodes");
         }
     }
-}
\ No newline at end of file
+}