docs: public boolean containsThumbnail(int userPage, int page, float width, float height, RectF pageRelativeBounds) {
          PagePart fakePart = new PagePart(userPage, page, null, width, height, pageRelativeBounds, true, 0);
          for (PagePart part : thumbnails) {
              if (part.equals(fakePart)) {
                  return true;
              }
          }
          return false;
      }