@Nullable
  private static PropertiesFile extractPropertiesFileFromNode(TreeNode node) {
    if (!(node instanceof DefaultMutableTreeNode)) return null;
    final Object userObject = ((DefaultMutableTreeNode) node).getUserObject();
    if (!(userObject instanceof PsiFileNode)) return null;
    final PsiFile file = ((PsiFileNode)userObject).getValue();
    final PropertiesFile propertiesFile = PropertiesImplUtil.getPropertiesFile(file);
    if (propertiesFile == null || !file.getManager().isInProject(file) || !file.isValid()) return null;
    return propertiesFile;
  }
@Nullable
  private static PropertiesFile extractPropertiesFileFromNode(TreeNode node)