constructorDetector seems to invalidate defaultSetterInfo for nullability

[joca-bt]

Was trying out the new constructor detector feature (https://cowtowncoder.medium.com/jackson-2-12-most-wanted-3-5-246624e2d3d0/) and stumbled upon the following issue.

I had this code which forbids nulls on deserialization:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonSetter;
import com.fasterxml.jackson.annotation.Nulls;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;

public class Input {
    private final Boolean field;

    @JsonCreator
    public Input(Boolean field) {
        this.field = field;
    }
}

ObjectMapper objectMapper = JsonMapper.builder()
    .addModule(new ParameterNamesModule(JsonCreator.Mode.PROPERTIES))
    .defaultSetterInfo(JsonSetter.Value.construct(Nulls.FAIL, Nulls.FAIL))
    .build();

objectMapper.readValue("{ \"field\": null }", Input.class); // throws InvalidNullException, as expected

and was trying to get rid of @JsonCreator with the following

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonSetter;
import com.fasterxml.jackson.annotation.Nulls;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.cfg.ConstructorDetector;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;

public class Input {
    private final Boolean field;

    // @JsonCreator gone!
    public Input(Boolean field) {
        this.field = field;
    }

    public Boolean field() {
      return field;
    }
}

ObjectMapper objectMapper = JsonMapper.builder()
    .addModule(new ParameterNamesModule(JsonCreator.Mode.PROPERTIES))
    .constructorDetector(ConstructorDetector.USE_PROPERTIES_BASED) // new!
    .defaultSetterInfo(JsonSetter.Value.construct(Nulls.FAIL, Nulls.FAIL))
    .build();

objectMapper.readValue("{ \"field\": null }", Input.class); // no error, field is assigned to null

Although I no longer need to annotate my class with @JsonCreator, my settings for nullability are ignored, which means I can't really use the new feature.

(Might be related with https://github.com/FasterXML/jackson-databind/issues/3227?)

[cowtowncoder]

Yes, I can reproduce this. Strange... It is possible this is due to implicit detection of constructors missing some information that would be discovered by explicitly marker ones.

[joca-bt]

This is particularly annoying when using records as we need to do something like:

public record Input(Boolean field) {
    @JsonCreator
    public Input {}
}

Do you think this fix can be included in 2.14?

[cowtowncoder]

As soon as someone provides a fix, yes, it could probably be included in a 2.13.x patch as well. I haven't had and probably won't have time to work in this in near future.

[cowtowncoder]

Sigh. Yes, I think this is because of the disprepancy between merging of annotations between explicitly annotated and implicitly located Creators: this is a long-standing general problem that manifests in many different ways.

On plus side: if and when property introspection gets rewritten (it is #1 top Big Thing for me to fix) this problem will be resolved. On downside: I have not been able to find enough time to start the rewrite.

[yihtserns]

This is particularly annoying when using records as we need to do something like:

public record Input(Boolean field) {
   @JsonCreator
   public Input {}
}

• For Record: With 2.15.0 (which contains #3724), you no longer need to annotate your Record's canonical constructor with @JsonCreator - it will just work (or rather, fail with InvalidNullException).
• For POJO: Not fixed yet.