Function make_millis_to_ts_ntz_udf 

pub fn make_millis_to_ts_ntz_udf() -> ScalarUDF

millis_to_ts_ntz(millis) — INT64 milliseconds since epoch → timezone-naive microsecond timestamp (Timestamp(µs, None)).

The tz-naive counterpart of make_millis_to_ts_udf, safe to write into Delta TIMESTAMP_NTZ columns. Semantically matches DataFusion’s built-in to_timestamp_millis; provided under the Spark-compat name so existing millis_to_ts(...) call sites migrate with a one-token edit.