[karaf] Fix NPE in the OBR refreshUrl command

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@911484 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/karaf/shell/obr/src/main/java/org/apache/felix/karaf/shell/obr/RefreshUrlCommand.java b/karaf/shell/obr/src/main/java/org/apache/felix/karaf/shell/obr/RefreshUrlCommand.java
index a4d7e2e..888d6f8 100644
--- a/karaf/shell/obr/src/main/java/org/apache/felix/karaf/shell/obr/RefreshUrlCommand.java
+++ b/karaf/shell/obr/src/main/java/org/apache/felix/karaf/shell/obr/RefreshUrlCommand.java
@@ -31,7 +31,7 @@
     List<String> urls;
 
     protected void doExecute(RepositoryAdmin admin) throws Exception {
-		if (urls != null || urls.isEmpty()) {
+		if (urls != null && !urls.isEmpty()) {
 			for (String url : urls) {
 				admin.removeRepository(new URL(url));
 				admin.addRepository(new URL(url));