private static Collection<PsiFile> convertToFiles(Collection<? extends BasePsiNode<? extends PsiElement>> formNodes) {
    List<PsiFile> psiFiles = new ArrayList<>();
    for (AbstractTreeNode<?> treeNode : formNodes) {
      psiFiles.add((PsiFile)treeNode.getValue());
    }
    return psiFiles;
  }
private static Collection<PsiFile> convertToFiles(Collection<? extends BasePsiNode<? extends PsiElement>> formNodes)