`BasicRelationalConverter` converts enum arrays to `null`

[jurriaan]

Opening a new ticket since I cannot reopen #1544 and the issue seems to also be present in the latest 3.0.x releases.

When updating from Spring v3.0.x to v3.1.1 we get the following database error when trying to persist an empty list of an enum type (kotlin emptyList()) to an array column in PostgreSQL:

null value in column "foo" of relation "bar" violates not-null constraint

I've created a small example project with a test that can reproduce the issue. It shows that it's not possible to persist arrays of enums, whether they are empty or not on spring-boot 3.0.9/3.1.x, but can on earlier spring boot versions:

https://github.com/jurriaan/issue-1544

[mp911de]

Thanks for the reproducer. It contained the missing bit of retaining the enum type which has led to conversion into the null value.

The fix is now deployed as part of the latest 3.0.x, 3.1.x and 3.2.0 snapshots if you want to verify that the fix is working for you. Make sure to upgrade both, R2DBC and Relational artifacts.

[jurriaan]

Thanks a lot for the quick fix!