feat: add support for enums serialized as JSON objects with @JsonFormat

[Mattias-Sehlstedt]

Pull Request

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Description

Adds so that @JsonFormat(shape = JsonFormat.Shape.OBJECT) is supported for enums.

The change means that enum

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum ObjectShapeEnum {
  FIRST(1, "one"),
  SECOND(2, "two");

  private final int code;

  private final String label;

  ObjectShapeEnum(int code, String label) {
    this.code = code;
    this.label = label;
  }

  public int getCode() {
    return code;
  }

  public String getLabel() {
    return label;
  }
}

is introspected to

"ObjectShapeEnum" : {
  "properties" : {
    "code" : {
      "format" : "int32",
      "type" : "integer"
    },
    "label" : {
      "type" : "string"
    }
  },
  "type" : "object"
}

instead of

"ObjectShapeEnum" : {
  "enum" : [ "FIRST", "SECOND" ],
  "type" : "string"
}

Fixes: #4506 #3691 #5287

Type of Change

• 🐛 Bug fix
• ✨ New feature
• ♻️ Refactor (non-breaking change)
• 🧪 Tests
• 📝 Documentation
• 🧹 Chore (build or tooling)

Checklist

• I have added/updated tests as needed
• I have added/updated documentation where applicable
• The PR title is descriptive
• The code builds and passes tests locally
• I have linked related issues (if any)

Screenshots / Additional Context