<https://github.com/FasterXML/jackson-module-kotlin/issues/192>

# jackson-kotlin

[rrader]

https://github.com/FasterXML/jackson-module-kotlin/issues/192

[diesieben07]

What you want is not possible. Even if Kotlin does not emit runtime type assertions, as far as Kotlin reflection is concerned, the type is still e.g. String, which cannot be null.

[diesieben07]

If you want null to end up in a property at all, the property must have a nullable type. Hacking around with disabling the assertions is a terrible idea. You will receive random NullPointerExceptions in places. The assertions have a reason...

[rrader]

no, the validation will be done by other tool, like @NotNull annotation

[rrader]

why is it not possible? the library just should check if kotlin throw any exceptions

[diesieben07]

The library checks the types reported by Kotlin reflection.

[diesieben07]

Those are still not-null.

[diesieben07]

Validation and type-system are different things. Just because the values are validated, they still can be null as far as the compiler is concerned.

[rrader]

The library checks the types reported by Kotlin reflection.

Why? Why just not to pass them to constructor and check the exception?

[rrader]

Validation and type-system are different things

in this case they are the same, both do validation

[rrader]

but kotlin intrisics fail on first argument, @NotNull can return all arguments that violate contract