private @NotNull PsiElement getParentNotNull(@NotNull String methodName) {
    if (myParent != null) {
      return myParent;
    }
    throw PluginException.createByClass(
      new AbstractMethodError("Elements initialized with `null` parent are expected to override `#" + methodName + "`"),
      getClass()
    );
  }
private @NotNull PsiElement getParentNotNull(@NotNull String methodName)