java zoneddatetime toEpochSecond without converting to local time

I have a dataset that is in EST time without any daylight saving.
Each datetime is read from string and a zonedDatetime is created using

ZonedDateTime java.time.ZonedDateTime.of(int year, int month, int dayOfMonth, int hour, int minute, int second, int nanoOfSecond, ZoneId zone)

with a ZoneId.of("America/New_York");

I need to convert these to an epoch second but the built in toEpochSecond method converts to my local time which is BST with day light saving. As a result the timestamps are four to five hours off depending on time of year. Is there a way to get a unix timestamp that does not take into account any local time so the timestamp matches the datetime in the original string?

> I need to convert these to an epoch second but the built in
> toEpochSecond method converts to my local time which is BST with day
> light saving. As a result the timestamps are four to five hours off
> depending on time of year.

You must be doing something fundamentally wrong. Check the output of the following code and you will find that there is no difference.

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.util.Locale;

public class Main {
	public static void main(String[] args) {
		// Formatter ignoring nanoseconds
		DateTimeFormatter formatter = new DateTimeFormatterBuilder()
						                .appendPattern("uuuu-MM-dd'T'HH:mm:ssXXX")
						                .optionalStart()
						                .appendLiteral('[')
						                .parseCaseSensitive()
						                .appendZoneRegionId()
						                .appendLiteral(']')
						                .toFormatter(Locale.ENGLISH);

		// The given time-zone
		ZoneId zone = ZoneId.of("America/New_York");

		ZonedDateTime zdtNow = ZonedDateTime.now(zone);
		System.out.println(zdtNow.format(formatter));

		// Epoch seconds from ZonedDateTime
		long epochSecond = zdtNow.toEpochSecond();
		System.out.println(epochSecond);

		// ZonedDateTime from epoch seconds
		ZonedDateTime zdtFromEpochSeconds = Instant.ofEpochSecond(epochSecond).atZone(zone);
		System.out.println(zdtFromEpochSeconds.format(formatter));
	}
}

Output:

2020-09-28T17:31:23-04:00[America/New_York]
1601328683
2020-09-28T17:31:23-04:00[America/New_York]

To convert ZonedDateTime to Unix epoch time stamp

Convert first to java.time.Instant and then set zone offset to UTC, before converting it to epoch seconds, see below:

zonedDateTime.toInstant().atZone(ZoneOffset.UTC).toEpochSecond();

Note: The variable zonedDateTime is of type java.time.ZonedDateTime and can be in any time zone before converting it to "Unix epoch time stamp" in seconds.