// private methods
 private IWriteOperation <BsonDocument> CreateOperation(IChannel channel)
 {
     if (SupportedFeatures.IsCreateIndexesCommandSupported(channel.ConnectionDescription.ServerVersion))
     {
         return(new CreateIndexesUsingCommandOperation(_collectionNamespace, _requests, _messageEncoderSettings));
     }
     else
     {
         return(new CreateIndexesUsingInsertOperation(_collectionNamespace, _requests, _messageEncoderSettings));
     }
 }