DateTime Conversion (openHAB 3.x)

Can anyone give me a hint so I can do conversion #4?
I’ve tried to use datetime parser to convert a datetimetype to a Java time, but it won’t work.
I want to use now.isAfter(item state).
Example (works in OH 2.5.x):

val morning=new DateTime(Morning_Time.state.toString)
val day=new DateTime(Day_Time.state.toString)
var curr=""
if (now.isAfter(morning) && now.isBefore(day)) { curr="Morning"}

Because now is in OH3 Java time, this won’t work anymore.
I’ve tried to change it to this:

val morning=ZonedDateTime.parse(Morning_Time.state.toString, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
val day=ZonedDateTime.parse(Day_Time.state.toString, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
var curr=""
if (now.isAfter(morning) && now.isBefore(day)) { curr="Morning"}

But I get the error that it can’t be parse correctly.