code: @Override
  	public Map<String, MongoSession> findByIndexNameAndIndexValue(String indexName, String indexValue) {
  
  		return Optional.ofNullable(this.mongoSessionConverter.getQueryForIndex(indexName, indexValue))
  				.map(query -> this.mongoOperations.find(query, Document.class, this.collectionName))
  				.orElse(Collections.emptyList()) //
  				.stream() //
  				.map(dbSession -> convertToSession(this.mongoSessionConverter, dbSession))
  				.collect(Collectors.toMap(MongoSession::getId, mapSession -> mapSession));
  	}
docs: Currently this repository allows only querying against {@code PRINCIPAL_NAME_INDEX_NAME}.
  
  @param indexName the name if the index (i.e. {@link FindByIndexNameSessionRepository#PRINCIPAL_NAME_INDEX_NAME})
  @param indexValue the value of the index to search for.
  @return sessions map