add clean index to indices

modules/elasticsearch/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -60,4 +60,9 @@ public interface IndicesService extends Iterable<IndexService>, LifecycleCompone
     IndexService createIndex(String index, Settings settings, String localNodeId) throws ElasticSearchException;
 
     void deleteIndex(String index) throws ElasticSearchException;
+
+    /**
+     * Cleans the index without actually deleting any content for it.
+     */
+    void cleanIndex(String index) throws ElasticSearchException;
 }

modules/elasticsearch/src/main/java/org/elasticsearch/indices/InternalIndicesService.java

@@ -201,7 +201,11 @@ public class InternalIndicesService extends AbstractLifecycleComponent<IndicesSe
         return indexService;
     }
 
-    public synchronized void deleteIndex(String index) throws ElasticSearchException {
+    @Override public synchronized void cleanIndex(String index) throws ElasticSearchException {
+        deleteIndex(index, false);
+    }
+
+    @Override public synchronized void deleteIndex(String index) throws ElasticSearchException {
         deleteIndex(index, true);
     }