private boolean isOkBeginningOfPagesInDocumentList() {
    int listSize = documentOfPagesModel.getPagesAmount();

    if (listSize < 1) {
      return true;
    }

    long numberOfPage0 = documentOfPagesModel.getPageByIndex(0).getPageNumber();
    if (numberOfPage0 != targetVisiblePosition.pageNumber - 2
        && numberOfPage0 != targetVisiblePosition.pageNumber - 1) {
      // we can have no any extra pages before visible one only in case, when target visible page is in the beginning of the file
      return numberOfPage0 == targetVisiblePosition.pageNumber
             && targetVisiblePosition.pageNumber == 0;
    }

    if (listSize < 2) {
      return true;
    }

    long numberOfPage1 = documentOfPagesModel.getPageByIndex(1).getPageNumber();
    if (numberOfPage1 == targetVisiblePosition.pageNumber) {
      return true;
    }
    if (numberOfPage1 != targetVisiblePosition.pageNumber - 1) {
      return false;
    }

    if (listSize < 3) {
      return true;
    }

    long numberOfPage2 = documentOfPagesModel.getPageByIndex(2).getPageNumber();
    return numberOfPage2 == targetVisiblePosition.pageNumber;
  }
private boolean isOkBeginningOfPagesInDocumentList()