Convert GMT UTC EpochSec to ZonedDateTime in chosen timezone

TimeZoneUtils.java

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

/**
 * Timezone Conversion Utils between EpochSec Timestamps
 * and other date formats
 */
public class TimeZoneUtils {

    /**
     * Convert from UTC EpochSeconds to String DateTime in chosen Timezone
     * @param epochSec Epoch Seconds Unix Timestamp
     * @param timezone ZoneId Timezone
     * @return String DateTime in chosen Timezone
     */
    public static String toZonedDateTime(long epochSec, String timezone){
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        ZoneId zoneId = ZoneId.of(timezone);
        Instant instant = Instant.ofEpochSecond(epochSec);
        ZonedDateTime tzDt = ZonedDateTime.ofInstant(instant, zoneId);
        return tzDt.format(formatter);
    }
}