code: public String getSubProtocolsAsCSV() {
          if (subProtocols == null) {
              return null;
          }
  
          String subProtocolsAsCSV = "";
          for (String subProtocol : subProtocols) {
              subProtocolsAsCSV = subProtocolsAsCSV.concat(subProtocol + ",");
          }
          subProtocolsAsCSV = subProtocolsAsCSV.substring(0, subProtocolsAsCSV.length() - 1);
          return subProtocolsAsCSV;
      }
docs: Get sub protocols as a comma separated values string.
  
  @return a string of comma separated values of sub protocols.