Disallow empty singleton IDs

1 files changed, 2 insertions, 2 deletions

diff --git a/zkfacade/src/main/java/com/yahoo/vespa/curator/SingletonManager.java b/zkfacade/src/main/java/com/yahoo/vespa/curator/SingletonManager.java
index dd7d86bd26d..3bff9a1c3e0 100644
--- a/zkfacade/src/main/java/com/yahoo/vespa/curator/SingletonManager.java
+++ b/zkfacade/src/main/java/com/yahoo/vespa/curator/SingletonManager.java
@@ -46,8 +46,8 @@ class SingletonManager implements AutoCloseable {
     }
 
     synchronized CompletableFuture<?> register(String singletonId, SingletonWorker singleton) {
-        if (singletonId.contains("/") || singletonId.contains("..")) {
-            throw new IllegalArgumentException("singleton ID may not contain '/' or '..', but got " + singletonId);
+        if (singletonId.isEmpty() || singletonId.contains("/") || singletonId.contains("..")) {
+            throw new IllegalArgumentException("singleton ID must be non-empty, and may not contain '/' or '..', but got " + singletonId);
         }
         String old = registrations.putIfAbsent(singleton, singletonId);
         if (old != null) throw new IllegalArgumentException(singleton + " already registered with ID " + old);