Store ZonedDateTimeConverter as timestamp using JPA

ZonedDateTimeConverter.java

/*
 * Store Java 8 ZonedDateTimeConverter as Timestamp in the database.
 * Set `hibernate.jdbc.time_zone = UTC` so the timezone is set to UTC.
 */

package info.modprobe.cwp.data;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;
import java.time.ZoneId;
import java.time.ZonedDateTime;

import static java.util.Optional.ofNullable;

@Converter(autoApply = true)
public class ZonedDateTimeConverter implements AttributeConverter<ZonedDateTime, java.sql.Timestamp> {

    @Override
    public java.sql.Timestamp convertToDatabaseColumn(final ZonedDateTime entityValue) {
        return  ofNullable(entityValue)
                .map(entityTime -> entityTime.toInstant())
                .map(java.sql.Timestamp::from)
                .orElse(null);
    }

    @Override
    public ZonedDateTime convertToEntityAttribute(final java.sql.Timestamp databaseValue) {
        return ofNullable(databaseValue)
                .map(databaseTime -> databaseTime.toLocalDateTime())
                .map(localDateTime -> localDateTime.atZone(ZoneId.of("UTC")))
                .orElse(null);
    }
}