The Hibernate 6.2 Migration Guide describes changes between 6.1.x and 6.2.x. However, it does not provide any information about how to deal with the removal of AbstractPostInsertGenerator (Hibernate 6.1 Javadoc).

Because the removal is not documented, users are unable to determine how to migrate their projects that are using it.

This also impacts IdentityGenerator, which no longer has AbstractPostInsertGenerator as a superclass and thus does not inherit implementations of the methods determineBulkInsertionIdentifierGenerationSelectFragment(), generate(), and supportsBulkInsertionIdentifierGeneration() (see 6.1 Javadocs and 6.2 Javadocs).

Example of Impact

IdentityGenerator no longer has an implementation of generate() because it no longer inherits from AbstractPostInsertGenerator. In our project, we have code like this:

public class FooIdentityGenerator extends IdentityGenerator {
    @Override
    public Object generate​(SharedSessionContractImplementor s, Object obj) {
        if (...) {
            return ...;
        } else {
            return super.generate(implementor, obj);
        }
    }
}

Because IdentityGenerator no longer has an implementation of generate(), the @Override and the super.generate() are both broken.

Without anything in the Migration Guide on how to mitigate this, we are unsure how to fix our project so we can upgrade to Hibernate 6.2.

Additional Notes

AbstractPostInsertGenerator was not deprecated, was not on the internals list, and was not on the incubating list. Therefore, it is both surprising that it was removed, and noteworthy that it is not on the migration guide.