Spring Cached value is not of required type for Kotlin Boolean

AbstractValueAdaptingCache.get checks whether the requested type matches with the value type in the cache. This fails for Kotlin Boolean value type. The usage is as follows:

Cache spec: maximumSize=100,expireAfterWrite=5s

myCache.putIfAbsent(uuid, true) // uuid is a string
myCache.get(uuid, Boolean::class.java)

The type in AbstractValueAdaptingCache.get shows up as boolean, which seems to be the problem, but is correct according to Kotlin docs.

On the JVM, non-nullable values of this type are represented as values of the primitive type boolean.

I'm not aware of a way to use myCache.get with a nullable Boolean type that'd then be translated to Java Boolean wrapper type. Boolean?::class.java isn't valid Kotlin code.

Spring Boot 2.3.4.RELEASE, Spring 5.2.9.RELEASE, Caffeine cache 2.8.6.

Comment From: sbrannen

@sdeleuze, any thoughts on this one?

Comment From: sdeleuze

As you can see here: - kotlin.Boolean is mapped to Java boolean primitive type - kotlin.Boolean? is mapped to java.lang.Boolean

putIfAbsent is defined as public ValueWrapper putIfAbsent(Object key, @Nullable Object value) so when passing true the parameter in there is autoboxing and the type stored is java.lang.Boolean.

Boolean::class.java by default indeed returns the the primitive type but you can use Boolean::class.javaObjectType and your example will work as expected.

Based on that I think it works as expected and that we can close this issue. Please reopen with a more information if you think there is something we should fix.