TYPO3 Core

Currently objects which implement the Traversable interface are always persisted as CSV of their values after iterating. This change introduced this change of behavior with TYPO3 7.0.0. This is broken in various ways:

1. The type of the relation is ignored which could be e.g. ColumnMap::RELATION_HAS_ONE, thus multivalue does not make sense.
2. If an object implements DomainObjectInterface it must always be persisted using its identifier.

While I'm not sure how to handle the first case the second one should be fixed right away since it breaks persistence of objects which implement both Traversable as well as DomainObjectInterface