presto-main/src/main/java/io/prestosql/operator/index/PageRecordSet.java/PageRecordCursor/getObject
class PageRecordCursor:        @Override
        public Object getObject(int field)
        {
            checkState(position >= 0, "Not yet advanced");
            checkState(position < page.getPositionCount(), "Already finished");
            Type type = types.get(field);
            return type.getObject(page.getBlock(field), position);
        }