Deleting an object with a read-only flattened relationship fails

When commiting a delete for an object that has a read-only flattened relationship with NO_ACTION as the delete rule, that relationship still seems to be processed causing the following exception to be thrown:

org.apache.cayenne.CayenneRuntimeException:[v.2.0.2 January 14 2007] Cannot unset the read-only flattened relationship fullTextLanguagesArray
org.apache.cayenne.access.DataDomainIndirectDiffBuilder.arcDeleted(DataDomainIndirectDiffBuilder.java:128)

After doing some debugging, it seems that problem is coming from the DataContextDeleteAction class, because it is setting the processFlattened as true. It only takes a look at whether it is a flattened relationship and if the relationship is to a dependent entity, but doesn't look at whether it is read only or not. This causes the objectStore.recordArcDeleted() to be called for the object related through this flattened read-only relationship.

In our case, this flattened relationship (fullTextLanguagesArray) has a relationship path that takes it through 4 relationships, so it's definitely a read-only flattened relationship. I can also say this for sure, because the DataDomainIndirectDiffBuilder.arcDeleted checks whether the relationship is flattened and read-only, and that's when the exception is thrown.

I would think that changing:

boolean processFlattened = relationship.isFlattened() && relationship.isToDependentEntity();

to

boolean processFlattened = relationship.isFlattened() && relationship.isToDependentEntity() && !relationship.isReadOnly();

would fix the issue.

Please let me know if you need any details. I would be really interested to have this fixed in a patch release of 2.0 soon, since it is preventing us from using one part of our system.