`@JsonProperty` on constructor parameter changes default field serialization order

[pjfanning]

Discussed in #3925

^{Originally posted by safdevke May 12, 2023}
Hi, this is a trivial case that I came across. Using nested records changes the order of the properties in the serialized output. Here's a simple example:

public record NestedRecordOne(
    String id,

    String email,

    @JsonProperty(value = "yikes!")
    NestedRecordTwo nestedRecordTwo) {}

public record NestedRecordTwo (
    String id,

    String passport) {}

public static void main(String[] args) throws IOException {

        ObjectMapper objectMapper = new ObjectMapper();
        NestedRecordTwo nestedRecordTwo = new NestedRecordTwo("2", "111110");
        NestedRecordOne nestedRecordOne = new NestedRecordOne("1", "test@records.com", nestedRecordTwo);

        objectMapper.writeValue(new File("nested-record.json"), nestedRecordOne);
    }

The output is:

{
    "yikes!": {
        "id": "2",
        "passport": "111110"
    },
    "id": "1",
    "email": "test@records.com"
}

Performing the same test on classes seems to work fine:

public class NestedClassOne {

    private String id;

    private String name;

    @JsonProperty(value = "all is fine!")
    private NestedClassTwo nestedClassTwo;

    // All args constructor + getters + setters
}

public class NestedClassTwo {

    private String id;

    // All args constructor + getters + setters
}

    NestedClassOne nestedClassOne = new NestedClassOne("1", new NestedClassTwo("2"), "test class");
    
    objectMapper.writeValue(new File("nested-class.json"), nestedClassOne);

Produces:

{
    "id": "1",
    "name": "test class",
    "all is fine!": {
        "id": "2"
    }
}

This could be easily fixed by using @JsonPropertyOrder. I wonder why it behaves this way for records. I didn't think this warranted creating an issue.

[pjfanning]

@cowtowncoder I tested this and created a PR to add a test for the case where no annotations are used (and the order is correct - the field order in the record). When the JsonProperty is added to one field, then that appears to break the order.

[yihtserns]

More accurately, "@JsonProperty on constructor parameter interferes with default property order" whether it is Record or non-Record class - see #3925 (comment).

[JooHyukKim]

"@JsonProperty on constructor parameter interferes with default property order"

Quite accurate analysis of the problem, which is good👍🏻, but suggested title seems to cover only internal side of the problem. Where as current title takes more of the higher level view, easier to scroll through PR/Issue list and anticipate what happened in detail.

But then again. What I am saying is still subjective.

[pjfanning]

fix will be in 2.16.0