I'm trying to understand this error message during...

# jackson-kotlin

[bookwormat]

I'm trying to understand this error message during jackson deserialization with the Kotlin module:

"com.fasterxml.jackson.databind.JsonMappingException: Instantiation of [simple type, class at.example.MyClass] value failed (java.lang.IllegalArgumentException): Parameter specified as non-null is null: method at.example.MyClass.<init>, parameter optionalItems"

class declaration looks like this:

data class MyClass(val id: String, var optionalItems:List<Item> = listof())

the json input does not contain the optionalItems property, but I expected jackson to ignore the property, and my instance to be initalized with the default value.