code: public ClientSession startSession(final ClientSessionOptions options) {
          ClientSession clientSession = createClientSession(notNull("options", options));
          if (clientSession == null) {
              throw new MongoClientException("Sessions are not supported by the MongoDB cluster to which this client is connected");
          }
          return clientSession;
      }
docs: Creates a client session.
  
  @param options the options for the client session
  @return the client session
  @throws MongoClientException if the MongoDB cluster to which this client is connected does not support sessions
  @mongodb.server.release 3.6
  @since 3.6