Message Title

catch very unexpected exception while updgrading hibernate version 5.2.12 -> 5.2.15
in scenario when
there are object whith null OneToOne property in database
and it is updated with object with non null OneToOne property.

Caused by: org.hibernate.id.IdentifierGenerationException: attempted to assign id from null one-to-one property [models.Secunda.parent]
	at org.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:90)
	at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:105)
	at org.hibernate.jpa.event.internal.core.JpaMergeEventListener.saveWithGeneratedId(JpaMergeEventListener.java:56)
	at org.hibernate.event.internal.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:255)
	at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:235)
	at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:173)
	at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:905)
	at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:875)
	at org.hibernate.engine.spi.CascadingActions$6.cascade(CascadingActions.java:261)
	at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:467)
	at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:392)
	at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
	at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:126)
	at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:461)
	at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:327)
	at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:170)
	at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:69)
	at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:883)
	at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:869)