presto-main/src/main/java/io/prestosql/operator/index/PageBufferOperator.java/PageBufferOperator/createOperator
class PageBufferOperator:        @Override
        public Operator createOperator(DriverContext driverContext)
        {
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, planNodeId, PageBufferOperator.class.getSimpleName());
            return new PageBufferOperator(operatorContext, pageBuffer);
        }