code: public final String csv() {
          StringBuilder sb = new StringBuilder();
          String header =
                  "#RunID, ClientID, MsgCount, MsgBytes, MsgsPerSec, BytesPerSec, DurationSecs";
  
          sb.append(String.format("%s stats: %s\n", name, this));
          sb.append(header); sb.append("\n");
          sb.append(csvLines(subs,"S"));
          sb.append(csvLines(pubs,"P"));
          return sb.toString();
      }
docs: Returns a string containing the report as series of CSV lines.
  
  @return a string with multiple lines