@Nullable
  private PsiElement getFirstNonMarkerElement() {
    final var marker = getMarkerElement();
    if (marker == null) {
      return null;
    }
    final var next = marker.getNextSibling();
    if (next != null && PsiUtilCore.getElementType(next) == MarkdownTokenTypes.CHECK_BOX) {
      return next.getNextSibling();
    }
    return next;
  }
@Nullable
  private PsiElement getFirstNonMarkerElement()