Fix problem with cluter not forming

Change-Id: Iea3ad0b5dd3367ed88663cf5ade3f81aacc2bfce
diff --git a/core/net/src/main/java/org/onosproject/cluster/impl/ClusterMetadataManager.java b/core/net/src/main/java/org/onosproject/cluster/impl/ClusterMetadataManager.java
index 416bbf14..ec64d3e 100644
--- a/core/net/src/main/java/org/onosproject/cluster/impl/ClusterMetadataManager.java
+++ b/core/net/src/main/java/org/onosproject/cluster/impl/ClusterMetadataManager.java
@@ -131,7 +131,7 @@
         String metadataUri = System.getProperty("onos.cluster.metadata.uri");
         try {
             String protocol = metadataUri == null ? null : new URL(metadataUri).getProtocol();
-            if (!"file".equals(protocol) && !"http".equals(protocol)) {
+            if (protocol != null && (!"file".equals(protocol) && !"http".equals(protocol))) {
                 return getProvider(protocol);
             }
             // file provider supports both "file" and "http" uris