jooq UTC localdatetime changes between save and load - postgresql

Question

My coworker created a postgresql database using jooq. Since then, we created objects with fields and the value of LocalDateTime.now(ZoneOffset.UTC). When those get saved to this database and read again later a few hours changed in our data object:
public class PlannedInvoice
{
private UUID accountId;
private LocalDateTime billingTime;
}
The save method looks similar to this:
LocalDateTime now = LocalDateTime.now(ZoneOffset.UTC);
UUID accountId = UUID.randomUUID();
PlannedinvoiceRecord record = plannedInvoiceService.create();
record.setAccountid(accountId.toString());
record.setBillingtime(now.atOffset(ZoneOffset.UTC));
record.store();
And the read method like this:
return dsl.selectFrom(PLANNEDINVOICE)
.where(PLANNEDINVOICE.ACCOUNTID.eq(accountId.toString()))
.fetchOneInto(PlannedInvoice.class);
The database uses timestamp with time zone currently, but I would also be happy to replace it with actual LocalDateTime to avoid these problems altogether(JOOQ supports this)!
When we save a value of LocalDateTime.of(2020, Month.AUGUST, 13, 0, 0), it will be 2020-08-12 20:00:00-04 in the database. This still seems correct.
Reading the value from the database seems where things go wrong. After the read method the value of billingTime is 2020-08-12 20:00:00. It seems to me like the time zone gets ignored by fetchOneInto when reconstructing the data object.
So why is there a conversion when saving UTC values and why is there no conversion when reading those back from the database? This seems very counterintuitive to me. I would prefer to avoid any time zone conversions at all.

Answer 1

What worked for me was to create a temporary read object with OffsetDateTime and then converting it using withOffsetSameInstant(ZoneOffset.UTC).toLocalDateTime(). It was rather easy in the end to fix it. It was just counterintuitive from the start, that the db and/or jooq would convert the data to other time zones.
This is the new object:
public class PlannedInvoiceWithOffset
{
private UUID accountId;
private OffsetDateTime billingTime;
}
A new constructor for creating the desired data object and adjusting the time zone to UTC:
public PlannedInvoice(PlannedInvoiceWithOffset tempObject)
{
this.accountId = tempObject.getAccountId();
this.billingTime = tempObject.getBillingTime().withOffsetSameInstant(ZoneOffset.UTC).toLocalDateTime();
}
Now my read method looks like this:
public PlannedInvoice findByAccountId(UUID accountId)
{
PlannedInvoiceWithOffset temp = dsl.selectFrom(PLANNEDINVOICE)
.where(PLANNEDINVOICE.ACCOUNTID.eq(accountId.toString()))
.fetchOneInto(PlannedInvoiceWithOffset.class);
return new PlannedInvoice(temp);
}