Function print_nulls

datafusion/functions-aggregate/src/array_agg.rs:1591–1595

(sort: Vec<Option<String>>)

    }

    fn print_nulls(sort: Vec<Option<String>>) -> Vec<String> {
        sort.into_iter()
            .map(|v| v.unwrap_or_else(|| "NULL".to_string()))
            .collect()
    }

    fn string_list_data<'a>(data: impl IntoIterator<Item = Vec<&'a str>>) -> ArrayRef {
        let mut builder = ListBuilder::new(StringBuilder::new());