Feature flag to serialize unitialized lateinit properties into null

[SButterfly]

Use case

We log entity classes before saving them to the database

data class MyEntity(
 val text: String,
... other required properties
) {
lateinit var createAt: Instant // this field is initialized after the entity is saved to the Database
}

fun save(entity: MyEntity) {
  log.info("About to save ${objectMapper.writeValueAsString(entity)}")
  repository.save(entity)
}

Describe the solution you'd like

A new feature flag

    val module = KotlinModule.Builder()
            .configure(KotlinFeature.UnintializedLateInitToNull, true) // to write them as nulls
            .configure(KotlinFeature.UnintializedLateInitToIgnore, true) // or to avoid them
          .build()

Describe alternatives you've considered

No response

Additional context

No response

[k163377]

It may be possible to achieve this, but needs to be investigated in detail.

First, the lateinit property and its decompiled result are as follows.
You can see that an error is always thrown when the getter is called.

class Dto { lateinit var name: String }

public final class Dto {
   public String name;

   @NotNull
   public final String getName() {
      String var1 = this.name;
      if (var1 != null) {
         return var1;
      } else {
         Intrinsics.throwUninitializedPropertyAccessException("name");
         return null;
      }
   }

   public final void setName(@NotNull String var1) {
      Intrinsics.checkNotNullParameter(var1, "<set-?>");
      this.name = var1;
   }
}

I can think of roughly two ways to make serialization work in this situation.

One is to ignore the getter and use the field for serialization.
The other is to hack the JsonFilter mechanism and display nothing if it is before initialization.

However, the feasibility of both has not been confirmed.
Also, it should be discussed how it should be handled based on consistency with functions such as JsonSetter(nullsUsing = ...).
For now, I feel that the policy of “serialize to undefined if not yet initialized” is the way to go, but I can understand the opinion that it should be serialized as null.