add toString() to CollectionRef

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1669153 13f79535-47bb-0310-9956-ffa450edef68

solr/solrj/src/java/org/apache/solr/common/cloud/ClusterState.java

@@ -391,6 +391,11 @@ public class ClusterState implements JSONWriter.Writable {
     }
 
     public boolean isLazilyLoaded() { return false; }
+    
+    @Override
+    public String toString() {
+      return coll.toString();
+    }
 
   }