How to validate a class not under my control in a web flux controller? I'm implementing PATCH and the controller function accepts a

@RequestBody @ValidJsonPatch patch: JsonPatch

I've created the validation annotation and constraint validator:

@Constraint(validatedBy = [JsonPatchValidator::class])
annotation class ValidJsonPatch(
    val message: String = "",
    val groups: Array<KClass<*>> = [],
    val payload: Array<KClass<out Payload>> = [],
)

class JsonPatchValidator : ConstraintValidator<ValidJsonPatch, JsonPatch> {
    override fun isValid(value: JsonPatch, context: ConstraintValidatorContext): Boolean { ... }
}

But the validator never gets invoked. I've added

_implementation_("org.springframework.boot:spring-boot-starter-validation")

to my dependencies and standard jakarta validation annotations work. edit: scratch that... standard validation annotations are also not working.

might need to add an @Validated to the controller function param

Nope. And sorry for the kotlin-not-kotlin Q. Realized that after.