public async Task <IEventIndexProcessor <TEvent> > AddAsync <TEvent, TSearchDocument>(
string indexName, Func <EventLog <TEvent>, TSearchDocument> mappingFunc,
IEnumerable <ITransactionHandler> functionHandlers = null) where TEvent : class, new()
where TSearchDocument : class, IHasId, new()
{
var indexer = await _elasticSearchService.CreateEventIndexer(indexName, mappingFunc);
_indexers.Add(indexer);
return(CreateProcessor(functionHandlers, indexer));
}