@Override
  public boolean validate(@Nullable Project currentProject, @NotNull Project project) {
    final Ref<Exception> refEx = new Ref<>();
    final Set<String> variables = new HashSet<>();
    final Map<String, String> naturesNames = new HashMap<>();
    final List<String> projectsToConvert = getParameters().projectsToConvert;
    final boolean oneProjectToConvert = projectsToConvert.size() == 1;
    final String separator = oneProjectToConvert ? "<br>" : ", ";
    ProgressManager.getInstance().runProcessWithProgressSynchronously(() -> {
      try {
        for (String path : projectsToConvert) {
          File classPathFile = new File(path, EclipseXml.DOT_CLASSPATH_EXT);
          if (classPathFile.exists()) {
            EclipseClasspathReader.collectVariables(variables, JDOMUtil.load(classPathFile), path);
          }
          collectUnknownNatures(path, naturesNames, separator);
        }
      }
      catch (IOException | JDOMException e) {
        refEx.set(e);
      }
    }, EclipseBundle.message("eclipse.import.converting"), false, null);

    if (!refEx.isNull()) {
      Messages.showErrorDialog(project, refEx.get().getMessage(), getTitle());
      return false;
    }

    if (!ProjectMacrosUtil.checkNonIgnoredMacros(project, variables)) {
      return false;
    }

    if (!naturesNames.isEmpty()) {
      final String title = EclipseBundle.message("notification.title.unknown.natures.detected");
      final String naturesByProject;
      if (oneProjectToConvert) {
        naturesByProject = naturesNames.values().iterator().next();
      }
      else {
        naturesByProject = StringUtil.join(naturesNames.keySet(), projectPath -> projectPath + "(" + naturesNames.get(projectPath) + ")", "<br>");
      }
      Notifications.Bus.notify(new Notification("Unknown Natures Detected", title, EclipseBundle
        .message("notification.content.imported.projects.contain.unknown.natures",
                 naturesByProject), NotificationType.WARNING));
    }

    return true;
  }
@Override
  public boolean validate(@Nullable Project currentProject, @NotNull Project project)