@Nullable
      @Override
      public ChangeApplier prepareChange(@NotNull List<? extends @NotNull VFileEvent> events) {
        Set<VirtualFile> toDelete = null;
        for (VFileEvent event : events) {
          if (event instanceof VFileDeleteEvent) {
            if (toDelete == null) {
              toDelete = new HashSet<>();
            }
            toDelete.add(event.getFile());
          }
        }
        if (toDelete == null) {
          return NO_OP;
        }
        Set<AntBuildFileBase> antFiles = null;
        for (AntBuildFileBase file : myBuildFiles) {
          if (toDelete.contains(file.getVirtualFile())) {
            if (antFiles == null) {
              antFiles = new HashSet<>();
            }
            antFiles.add(file);
          }
        }
        return antFiles == null? NO_OP : new FileDeletionChangeApplier(toDelete, antFiles);
      }
@Nullable
      @Override
      public ChangeApplier prepareChange(@NotNull List<? extends @NotNull VFileEvent> events)