A DESCRIPTION OF THE PROBLEM :
Epoch second is always from UTC, no matter which time zone you are, you have the same epoch second.
The comment below is from wikipedia:

the Unix epoch is 00:00:00 UTC on 1 January 1970

So, LocalDateTime internally should have an epoch time, and we should only provide toEpochSecond(), without zone offset parameter, it's wrong to have different epoch times in different time zones.