NullIsSameAsDefault is not respected for non-string types

[mroche89]

Describe the bug

When instantiating an objectmapper with the KotlinModule and setting the nullIsSameAsDefault to true, the setting is not respected for non-string types. When parsing json with explicit {"field":null}, we expect the field to have the default, and not be null (see below)

This reopens ticket 425

To Reproduce

The following test should pass (but does not):

@Test
fun `null inputs should use default value`() {
    val objectMapper = ObjectMapper().apply {
        registerModules(
            KotlinModule.Builder()
                .configure(KotlinFeature.NullIsSameAsDefault, true)
                .build()
        )
    }

    val json = """
        {
            "myBool": null,
            "myInt": null,
            "myStr": null,
            "myDouble": null,
            "myNullable": null,
            "myObj": null
        }
    """.trimIndent()
    println(objectMapper.readValue<MyObj>(json))
}

data class MyObj(
    val myBool: Boolean = true,
    val myInt: Int = 10,
    val myStr: String = "RedLeather",
    val myDouble: Double = 20.0,
    val myNullable: String? = null,
    val myObj: Inner = Inner()
) {
    data class Inner(val myVal: String = "YellowLeather")
}

This prints

MyObj(myBool=false, myInt=0, myStr=RedLeather, myDouble=0.0, myNullable=null, myObj=Inner(myVal=YellowLeather))

Only myStr, myNullable and myObj used correct defaults

Versions

Kotlin: 1.6.21
Jackson-module-kotlin: 2.13.4