public override void Merge(IndexWriter writer, MergeTrigger trigger, bool newMergesFound)
 {
     MergePolicy.OneMerge merge = null;
     while ((merge = writer.NextMerge) != null)
     {
         if (VERBOSE)
         {
             Console.WriteLine("executing merge " + merge.SegString(writer.Directory));
         }
         writer.Merge(merge);
     }
 }