[Bug]: http-client-java, difference on serialization of XML with namespace

[weidongxu-microsoft]

Describe the bug

test case https://github.com/microsoft/typespec/blob/main/packages/http-client-java/generator/http-client-generator-clientcore-test/src/test/java/payload/xml/XmlTests.java#L310-L334

test scenario https://github.com/microsoft/typespec/blob/main/packages/http-specs/specs/payload/xml/main.tsp#L461-L504

Java SDK serialize XML as e.g.

<ModelWithNamespaceOnProperties xmlns="http://example.com/schema" xmlns:smp="http://example.com/schema" xmlns:ns2="http://example.com/ns2">
  <id>123</id>
  <title>The Great Gatsby</title>
  <ns2:author>F. Scott Fitzgerald</ns2:author>
</ModelWithNamespaceOnProperties>

Validation is

<smp:ModelWithNamespaceOnProperties xmlns:smp="http://example.com/schema" xmlns:ns2="http://example.com/ns2">
  <id>123</id>
  <smp:title>The Great Gatsby</smp:title>
  <ns2:author>F. Scott Fitzgerald</ns2:author>
</smp:ModelWithNamespaceOnProperties>

The most disagreement is on the id property.

In Java serialization, id is in "http://example.com/schema" namespace.

While in test scenario, id is in null namespace.

---

code-model.yaml contains the info

    - &ref_86
      language:
        default:
          name: ModelWithNamespaceOnProperties
          description: >-
            §6.2, §7.2 — Contains fields with different XML namespaces on
            individual properties.
          namespace: Payload.Xml
          crossLanguageDefinitionId: Payload.Xml.ModelWithNamespaceOnProperties
        java:
          namespace: payload.xml
      protocol: {}
      type: object
      properties:
        - language:
            default:
              name: id
              description: ''
          protocol: {}
          schema: *ref_3
          serializedName: id
          required: true
          nullable: false
          readOnly: false
          serialization:
            xml:
              name: id
              attribute: false
              wrapped: false
              text: false
        - language:
            default:
              name: title
              description: ''
          protocol: {}
          schema: *ref_0
          serializedName: title
          required: true
          nullable: false
          readOnly: false
          serialization:
            xml:
              name: title
              namespace: http://example.com/schema
              prefix: smp
              attribute: false
              wrapped: false
              text: false
        - language:
            default:
              name: author
              description: ''
          protocol: {}
          schema: *ref_0
          serializedName: author
          required: true
          nullable: false
          readOnly: false
          serialization:
            xml:
              name: author
              namespace: http://example.com/ns2
              prefix: ns2
              attribute: false
              wrapped: false
              text: false
      serialization:
        xml:
          name: ModelWithNamespaceOnProperties
          namespace: http://example.com/schema
          prefix: smp
          attribute: false
          wrapped: false
          text: false
      usage:
        - output
        - public
        - input

Reproduction

Start the spector in "/packages/http-client-java/generator/http-client-generator-clientcore-test"

1. Setup.ps1
2. npm run spector-serve

Run the test

Checklist

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[weidongxu-microsoft]

Serialization from Java sets the "smp" as the default namespace (hence the model and title can skip the "smp" prefix). However, it seems cause the id in "smp" namespace too (where it should be in null namespace).

[weidongxu-microsoft]

TypeSpec doc https://typespec.io/docs/libraries/xml/guide/#5-namespace-and-prefix-inline-form
Swagger doc https://swagger.io/docs/specification/v3_0/data-models/representing-xml/

I think they are consistent. If no @ns on a property, it won't automatically inherit the namespace from model.