Properties without value should fail when iterating a domain object collection

[melix]

This is a regression which happened between 6.1 and 6.2.

Expected Behavior

When a property is added to a domain object collection, and that no value is provided for this property, iterating on the collection should fail with:

No value has been specified for this property.

(ideally it should say what property but there it has no name)

Current Behavior

Since 6.2, iterating on the collection works, the property is silently ignored, as if it wasn't added to the container. While it can be convenient, it's actually confusing.

Steps to Reproduce

Reproducer

@groovy.transform.Canonical
class Thing implements Named {
    final String name
}

def container = objects.domainObjectSet(Thing)

def provider = objects.property(Thing)

container.addLater(provider)

container.each { println it.name }

This script fails in 6.1, passes in 6.2.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Given the limited bandwidth of the team, it will be automatically closed if no further activity occurs. If you're interested in how we try to keep the backlog in a healthy state, please read our blog post on how we refine our backlog. If you feel this is something you could contribute, please have a look at our Contributor Guide. Thank you for your contribution.

[melix]

This behavior is still present in 7.4.1.

[alllex]

I think it's this change that introduced different behavior:
ec66818#diff-acd0c9c9cb69fc3c944be33befdde036f5f448a58517dd1b140fb25ac9a0a225R341-R344