Hi, I am the maintainer of `jackson-module-kotlin`...

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[wrongwrong]

Hi, I am the maintainer of jackson-module-kotlin.

We are planning to release Jackson 3.0.0-rc1 at the end of February.
In 3.0, the default values of some options will be changed based on user discussions.
Some of them are still open for voting, so please vote for them here.

The jackson-module-kotlin is being voted on as well, so please check it out.
• Enable `StrictNullChecks` by default
• Enable `SingletonSupport` by default
Suggestions for new changes are also welcome.

[Klitos Kyriacou]

Just so I understand properly, what exactly does the documentation mean by "Deserializing a singleton overwrites the value of the single instance"? Which instance is overwritten? The Kotlin object itself or the instance that's just been deserialized?

[wrongwrong]

I am not aware of what the intent of the KotlinFeature.SingletonSupport documentation was.

However, even if it was the default, I would not rewrite the INSTANCE field.
The only problem is that a new instance is created incorrectly each time it is deserialized.

[Klitos Kyriacou]

Thanks for the reply. My worry was what would happen if you serialize a singleton Kotlin object and then you change the object and then deserialize it back. I guess in such cases there's no completely safe thing to do, and the developer should guard against such possibilities.

[Klitos Kyriacou]

Another example that may cause unexpected behaviour:

object DontDoThis {
    Instance appStartTime = Instance.now()
}

A naive programmer may think they could save a start time in a file by doing the above.