private PackageDependenciesNode getParentModuleGroup(List<String> groupPath){
    final String key = StringUtil.join(groupPath, "");
    ModuleGroupNode groupNode = myModuleGroupNodes.get(key);
    if (groupNode == null) {
      groupNode = new ModuleGroupNode(new ModuleGroup(groupPath), myProject);
      myModuleGroupNodes.put(key, groupNode);
      myRoot.add(groupNode);
    }
    if (groupPath.size() > 1) {
      final PackageDependenciesNode node = getParentModuleGroup(groupPath.subList(0, groupPath.size() - 1));
      node.add(groupNode);
    }
    return groupNode;
  }
private PackageDependenciesNode getParentModuleGroup(List<String> groupPath)