docs: @Override
      public RegistrationManager getRegistrationManager(){
          if(registrationManager == null){
              synchronized(this){
                  if(registrationManager == null){
                      RegistrationManagerImpl registration = new RegistrationManagerImpl(getDirectoryServiceClientManager());
                      registration.start();
                      registrationManager = registration;
                  }
              }
          }
          return registrationManager;
      }