docs: private int getColumnSpan(final Attributes atts) {
          final String start = atts.getValue(ATTRIBUTE_NAME_NAMEST);
          final String end = atts.getValue(ATTRIBUTE_NAME_NAMEEND);
          if (start == null || end == null) {
              return 1;
          } else {
              final int ret = colSpec.indexOf(end) - colSpec.indexOf(start) + 1;
              if (ret <= 0) {
                  return 1;
              }
              return ret;
          }
      }