pool: ReplicaStoreCache updated to describe inner ReplicaStore

Motivation:

The toString method of the ReplicaStore is logged during startup.
Currently this uses the default (Object) method, which isn't
very helpful.

Modification:

Add ReplicaStoreCache#toString method

Result:

More meaningful information is logged.

Target: master
Requires-notes: no
Requires-book: no
Patch: https://rb.dcache.org/r/9717/
Acked-by: Gerd Behrmann

modules/dcache/src/main/java/org/dcache/pool/repository/ReplicaStoreCache.java

@@ -486,4 +486,10 @@ public long getTotalSpace()
     {
         return _inner.getTotalSpace();
     }
+
+    @Override
+    public String toString()
+    {
+        return _inner.toString();
+    }
 }