read absent optional value in empty

[DVMaslov]

fun main(args: Array<String>) {
    val mapper = ObjectMapper().apply {
        registerModule(Jdk8Module())
        registerModule(KotlinModule())
    }

    println(mapper.writeValueAsString(SomePatch(null, Optional.empty(), Optional.of("hello"))))
    println(mapper.readValue("{\"y\":null,\"z\":\"hello\"}", SomePatch::class.java))
}

@JsonInclude(JsonInclude.Include.NON_NULL)
data class SomePatch(
        val x: Optional<Int>?,
        val y: Optional<String>?,
        val z: Optional<String>?
)

output for version 2.9.6:

{"y":null,"z":"hello"}
SomePatch(x=null, y=Optional.empty, z=Optional[hello])

output for version 2.9.7:

{"y":null,"z":"hello"}
SomePatch(x=Optional.empty, y=Optional.empty, z=Optional[hello])

x absent in json but deserialize in Optional.empty

[cowtowncoder]

Since this is with Kotlin, I think this belongs under:

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

except that if it can be reproduced with just Java, then here.

[DVMaslov]

https://github.com/FasterXML/jackson-module-kotlin/issues/190