public long toEpochSecond() {
        long epochDay = toLocalDate().toEpochDay();
        long secs = epochDay * 86400 + toLocalTime().toSecondOfDay();
        secs -= getOffset().getTotalSeconds();
        return secs;
    }
public long toEpochSecond ( ) { long epochDay = toLocalDate ( ) . toEpochDay ( ) ; long secs = epochDay * 86400 + toLocalTime ( ) . toSecondOfDay ( ) ; secs -= getOffset ( ) . getTotalSeconds ( ) ; return secs ; }
Converts this date-time to the number of seconds from the epoch
of 1970-01-01T00:00:00Z.
<p>
This uses the {@linkplain #toLocalDateTime() local date-time} and
{@linkplain #getOffset() offset} to calculate the epoch-second value,
which is the number of elapsed seconds from 1970-01-01T00:00:00Z.
Instants on the time-line after the epoch are positive, earlier are negative.

@return the number of seconds from the epoch of 1970-01-01T00:00:00Z