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RedisIndexedSessionRepository nullability issues #3857
Description
Describe the bug
When upgrading to spring-session-data-redis 4.1.0 we can no longer call org.springframework.session.data.redis.RedisIndexedSessionRepository#setRedisSessionMapper to set a custom session mapper in Kotlin.
This is because the signature of redisSessionMapper expects the BiFunction to return a non-null MapSession, whereas before this was not the case (the result could be a null session).
Observing org.springframework.session.data.redis.RedisIndexedSessionRepository#getSession we see that the result of the BiFunction is expected to be a nullable value:
private @Nullable RedisSession getSession(String id, boolean allowExpired) {
// omitted for brevity
MapSession loaded = this.redisSessionMapper.apply(id, entries);
if (loaded == null || (!allowExpired && loaded.isExpired())) {
return null;
}
// omitted for brevity
}To Reproduce
The custom mapper below fails to compile in Kotlin because it returns null when loading an invalid session causes an IllegalStateException to be thrown:
@Bean
fun redisSessionRepositoryCustomizer() =
SessionRepositoryCustomizer<RedisIndexedSessionRepository> { redisSessionRepository ->
val delegate = RedisSessionMapper()
redisSessionRepository.setRedisSessionMapper { sessionId, map ->
try {
delegate.apply(sessionId, map)
} catch (_: IllegalStateException) {
redisSessionRepository.sessionRedisOperations.delete("${sessionDataRedisProperties.namespace}:sessions:$sessionId")
null
}
}
}Expected behavior
The custom mapper above should compile in Kotlin.
Sample
N/A
Activity
Mhmoud803 commentedon Jun 30, 2026
Hi team! It looks like we just missed a @nullable on the BiFunction for redisSessionMapper, which is making the Kotlin compiler complain. Since getSession is already built to handle nulls safely, this should be a pretty quick fix.
I'd love to pick this up! I can add the missing annotations and write a quick Kotlin test to prove the fix works. Just let me know if you're good with me opening a PR for this.
spring-projectsGH-3857: Allow redisSessionMapper to return null MapSe…
Allow RedisSessionMapper to Return Null