https://www.crnk.io/releases/stable/documentation/#_jsonapirelation
What is the need of @JsonApiRelationId as I see no difference without using it?
You can use @JsonApiRelationId
instead of @JsonApiRelation
when you just need to perate on ID, not on the entire related resource, or when the id of related resource can be obtain much cheaper then full resource.
Both could look like this:
public class Car {
...
@JsonApiRelationId
private Long ownerId;
@JsonApiRelation
private Person owner;