code: private String getLastSyncDate(Integer subscriptionId) {
          String lastSyncDate = null;
  
          TokenSyncDate tokenSyncDate = ocpiRepository.getTokenSyncDate(subscriptionId);
          if (tokenSyncDate != null) {
              lastSyncDate = AppConfig.DATE_FORMAT.format(tokenSyncDate.getSyncDate());
          }
  
          return lastSyncDate;
      }
docs: Returns the formatted datetime the tokens where last synchronized if it exists, otherwise null.
  
  @return last sync date if it exists, null otherwise