Missing value of type JsonNode? is deserialized as NullNode instead of null

[novtor]

Describe the bug
When in a kotlin data class a parameter is nullable, a payload with a missing value is desirialized and results in NullNode assigned to such a property

To Reproduce
kotlin:
data class TestDataClass(val jsonNodeValue: JsonNode?)
Java:
TestDataClass value = om.readValue("{}", TestDataClass.class); assertThat(value.getJsonNodeValue()).isNull();

Expected behavior
a missing optional value should be desirialized as null and not NullNode

Versions
Kotlin: 1.4
Jackson-module-kotlin: 2.11.4
Jackson-databind: 2.11.4

Additional context
PR: #491

[novtor]

some debates started here: FasterXML/jackson-databind#3214

[novtor]

I added some more test cases that fail even with my changes

[davidopluslau]

Hi! This is a great change and definitely the better default behavior. However, moving from 2.11 -> 2.13 was a breaking change for us, as we expected a Kotlin non-null value (previously a NullNode) and so threw at runtime. We've already fixed this by allowing null values, but it was a surprising change that required a non-trivial change. Is there any way to configure the object mapper to toggle between these two behaviors?

[cowtowncoder]

No, unfortunately there is not.