Why is deserialization with quarkus-panache, hibernate and jsonb failing?

I wanted to play around with hibernate, panache and quarkus a bit. I wanted to build a "tracing" api where a person can have several traces but a trace can only be owned by one person. but I am facing a deserialization error.

Let's say I want to post this:

curl --location --request POST 'localhost:8080/trace' \
--header 'Content-Type: application/json' \
--data-raw '{
    "traceOwner": "AtestOwner",
    "participants": ["Karl", "John"],
    "place": "10101, TestCity, TestStreet 25",
    "startTime": "2016-07-20T23:07:41.907+02:00[Europe/Berlin]",
    "stopTime": "2016-07-27T23:07:45.807+02:00",
    "comment": "TestComment"
}'

I get the following errors:

javax.ws.rs.ProcessingException: RESTEASY008200: JSON Binding deserialization error: javax.json.bind.JsonbException:
Unable to deserialize property 'traceOwner' because of: Error deserialize JSON value into type: class
de.test.Person.

and in the logs:

2020-07-27 10:48:12,597 SEVERE [org.ecl.yas.int.Unmarshaller] (executor-thread-1) Unable to deserialize property 'traceOwner' because of: Error deserialize JSON value into type: class de.test.Person.

My Entities look like this:

import java.time.ZonedDateTime;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.ManyToOne;

import io.quarkus.hibernate.orm.panache.PanacheEntity;

@Entity
public class Trace extends PanacheEntity {
  @ManyToOne
  public Person traceOwner;
  @ElementCollection
  public List<String> participants;
  public String place;
  @Column(columnDefinition = "TIMESTAMP WITH TIME ZONE")
  public ZonedDateTime startTime;
  @Column(columnDefinition = "TIMESTAMP WITH TIME ZONE")
  public ZonedDateTime stopTime;
  public String comment;

  public String toString() {
    return String.format("%s, [%s, %s], %s, %s, %s", this.traceOwner, this.participants.get(0),
        this.participants.get(1), this.place, this.startTime, this.stopTime, this.comment);
  }
}

and

import javax.persistence.Entity;

import io.quarkus.hibernate.orm.panache.PanacheEntity;

@Entity
public class Person extends PanacheEntity {
  public String name;
}

The POST endpoint looks like this:

  @POST
  @Produces(MediaType.APPLICATION_JSON)
  @Consumes(MediaType.APPLICATION_JSON)
  public Response createTrace(@Valid Trace trace) {
    try {
      LOG.info(trace);
      transaction.begin();
      trace.persist();
      transaction.commit();
    } catch (NotSupportedException | SystemException | SecurityException | IllegalStateException | RollbackException
        | HeuristicMixedException | HeuristicRollbackException e1) {
      LOG.error("Could not finish transaction to save entity", e1);
      return Response.status(HttpStatus.SC_BAD_REQUEST).build();

    }
    return Response.ok(Trace.find("startTime =?1 AND traceOwner = ?2", trace.startTime, trace.traceOwner).firstResult())
        .build();
  }

To avoid a caching problem I open a new transaction, but I guess that is not the problem?

I don't really get why jsonB complains about the deserialization and how I can fix it. Also, at some point I wanted public List<String> participants to be public List<Person> participants but that can wait till the relation and deserialization works.

So, I found out what I did do wrong. Two things:

1. Use a valid json:

curl --location --request POST 'localhost:8080/trace' \
--header 'Content-Type: application/json' \
--data-raw '{
    "traceOwner": {"name": "AtestOwner"},
    "participants": ["Karl", "John"],
    "place": "10101, TestCity, TestStreet 25",
    "startTime": "2016-07-20T23:07:41.907+02:00[Europe/Berlin]",
    "stopTime": "2016-07-27T23:07:45.807+02:00",
    "comment": "TestComment"
}'

Please notice the different "traceOwner" part.

2. Use @ManyToOne(cascade = CascadeType.ALL) to also update the transient property when persisting.