docs: public void appendLine(final Line line)
      {
          if (this.lineTail == null)
          {
              this.lines = this.lineTail = line;
          }
          else
          {
              this.lineTail.nextEmpty = line.isEmpty;
              line.prevEmpty = this.lineTail.isEmpty;
              line.previous = this.lineTail;
              this.lineTail.next = line;
              this.lineTail = line;
          }
      }