Structured Streaming window start time should support negative values to adjust time zone

I want to calculate (unique) daily access count using structured streaming (2.2.0).
Now strut streaming' s window with 1 day duration starts at
00:00:00 UTC and ends at 23:59:59 UTC each day, but my local timezone is CST (UTC + 8 hours) and I
want date boundaries to be 00:00:00 CST (that is 00:00:00 UTC - 8).

In Flink I can set the window offset to -8 hours to make it, but here in struct streaming if I set the start time (same as the offset in Flink) to -8 or any other negative values, I will get the following error:

Exception in thread "main" org.apache.spark.sql.AnalysisException: cannot resolve 'timewindow(timestamp, 86400000000, 86400000000, -28800000000)' due to data type mismatch: The start time (-28800000000) must be greater than or equal to 0.;;

because the time window checks the input parameters to guarantee each value is greater than or equal to 0.

So I'm thinking about whether we can remove the limit that the start time cannot be negative?