As for now, there is [check](https://github.com/spring-projects/spring-data-commons/blob/09281c7182e7801e85718814effb4ba79116c027/src/main/java/org/springframework/data/mapping/model/KotlinValueUtils.java#L219) for generic type if it's generic value class field, and that's working normally ```java nestedType.getClassifier() instanceof KTypeParameter ktp ``` but it fails with class cast exception when this constructor is being invoked with the KType parameter ```java private ValueBoxing(BoxingRules rules, KParameter parameter) { this(rules, parameter.getType(), (KClass<?>) parameter.getType().getClassifier(), parameter.isOptional()); } ``` Example data class : ```kotlin data class Foo<T>{val bar: T? = null) ```