presto-main/src/main/java/io/prestosql/operator/index/IndexSourceOperator.java/IndexSourceOperatorFactory/createOperator
class IndexSourceOperatorFactory:        @Override
        public SourceOperator createOperator(DriverContext driverContext)
        {
            checkState(!closed, "Factory is already closed");
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, sourceId, IndexSourceOperator.class.getSimpleName());
            return new IndexSourceOperator(
                    operatorContext,
                    sourceId,
                    index,
                    probeKeyNormalizer);
        }