code: public KSIBuilder setKsiProtocolExtenderClient(KSIExtenderClient extenderClient) {
          Util.notNull(extenderClient, "KSI Extender Client");
          return setKsiProtocolExtendingService(new KSIExtendingClientServiceAdapter(extenderClient));
      }
docs: Sets the extender client to be used in verification and extending process.
  
  @param extenderClient
  instance of {@link KSIExtenderClient}.
  @return Instance of {@link KSIBuilder}.