Tweak the way unindex tasks are logged

Only log after resolving indexer and indicate the name,
thus clearing any eventual confusion of this line appearing multiple times in repeat.

dicoogle/src/main/java/pt/ua/dicoogle/plugins/PluginController.java

@@ -771,8 +771,8 @@ public void unindex(URI path, Collection<String> indexProviders) {
      *         and whether some of them were not found in the database
      * @throws IOException
      */
-    public Task<UnindexReport> unindex(String indexProvider, Collection<URI> items, Consumer<Collection<URI>> progressCallback) throws IOException {
-        logger.info("Starting unindexing procedure for {} items", items.size());
+    public Task<UnindexReport> unindex(String indexProvider, Collection<URI> items,
+            Consumer<Collection<URI>> progressCallback) throws IOException {
 
         IndexerInterface indexer = null;
         if (indexProvider != null) {
@@ -781,6 +781,7 @@ public Task<UnindexReport> unindex(String indexProvider, Collection<URI> items,
         if (indexer == null) {
             indexer = this.getIndexingPlugins(true).iterator().next();
         }
+        logger.info("[{}] Starting unindexing procedure for {} items", indexer.getName(), items.size());
         Task<UnindexReport> task = indexer.unindex(items, progressCallback);
         if (task != null) {
             final String taskUniqueID = UUID.randomUUID().toString();