OAK-9338 RemotePersistentCacheService throws IllegalArgumentException if both redis and disk cache are disabled

Contribution by Axel Hanikel (ahanikel)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1885974 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/oak-segment-remote/src/main/java/org/apache/jackrabbit/oak/segment/remote/persistentcache/RemotePersistentCacheService.java b/oak-segment-remote/src/main/java/org/apache/jackrabbit/oak/segment/remote/persistentcache/RemotePersistentCacheService.java
index 4fd074a..b8c4aa3 100644
--- a/oak-segment-remote/src/main/java/org/apache/jackrabbit/oak/segment/remote/persistentcache/RemotePersistentCacheService.java
+++ b/oak-segment-remote/src/main/java/org/apache/jackrabbit/oak/segment/remote/persistentcache/RemotePersistentCacheService.java
@@ -60,7 +60,9 @@
     public void activate(ComponentContext context, Configuration config) throws IOException {
         osgiWhiteboard = new OsgiWhiteboard(context.getBundleContext());
         persistentCache = createPersistentCache(config, closer);
-        registration = context.getBundleContext().registerService(PersistentCache.class.getName(), persistentCache, new Properties());
+        if (persistentCache != null) {
+            registration = context.getBundleContext().registerService(PersistentCache.class.getName(), persistentCache, new Properties());
+        }
     }
 
     @Deactivate