presto-local-file/src/main/java/io/prestosql/plugin/localfile/LocalFileRecordCursor.java/LocalFileRecordCursor/getSlice
class LocalFileRecordCursor:    @Override
    public Slice getSlice(int field)
    {
        checkFieldType(field, createUnboundedVarcharType());
        return Slices.utf8Slice(getFieldValue(field));
    }