code: protected SingleBusLocatorRegistrar getRegistrar(Bus bus) {
          SingleBusLocatorRegistrar registrar = busRegistrars.get(bus);
          if (registrar == null) {
              check(locatorClient, "serviceLocator", "registerService");
              registrar = new SingleBusLocatorRegistrar(bus);
              registrar.setServiceLocator(locatorClient);
              registrar.setEndpointPrefix(endpointPrefix);
              Map<String, String> endpointPrefixes = new HashMap<String, String>();
              endpointPrefixes.put("HTTP", endpointPrefixHttp);
              endpointPrefixes.put("HTTPS", endpointPrefixHttps);
              registrar.setEndpointPrefixes(endpointPrefixes);
              busRegistrars.put(bus, registrar);
              addLifeCycleListener(bus);
          }
          return registrar;
      }
docs: Retrieves the registar linked to the bus.
  Creates a new registar is not present.
  
  @param bus
  @return