bug in YAML in property testing_criteria of type Eval

[zijianhuang]

In

    Eval:
      type: object
      title: Eval
      description: |
        An Eval object with a data source config and testing criteria.
        An Eval represents a task to be done for your LLM integration.
        Like:
         - Improve the quality of my chatbot
         - See how well my chatbot handles customer support
         - Check if o3-mini is better at my usecase than gpt-4o
      properties:
        object:
          type: string
          enum:
            - eval
          default: eval
          description: The object type.
          x-stainless-const: true
        id:
          type: string
          description: Unique identifier for the evaluation.
        name:
          type: string
          description: The name of the evaluation.
          example: Chatbot effectiveness Evaluation
        data_source_config:
          type: object
          description: Configuration of data sources used in runs of the evaluation.
          oneOf:
            - $ref: "#/components/schemas/EvalCustomDataSourceConfig"
            - $ref: "#/components/schemas/EvalStoredCompletionsDataSourceConfig"
        testing_criteria:
          default: eval
          description: A list of testing criteria.
          type: array
          items:
            oneOf:
              - $ref: "#/components/schemas/EvalLabelModelGrader"
              - $ref: "#/components/schemas/EvalStringCheckGrader"
              - $ref: "#/components/schemas/EvalTextSimilarityGrader"
              - $ref: "#/components/schemas/EvalPythonGrader"
              - $ref: "#/components/schemas/EvalScoreModelGrader"

default: eval seems like a bug:

        testing_criteria:
          default: eval
          description: A list of testing criteria.
          type: array
          items:
            oneOf:
              - $ref: "#/components/schemas/EvalLabelModelGrader"
              - $ref: "#/components/schemas/EvalStringCheckGrader"
              - $ref: "#/components/schemas/EvalTextSimilarityGrader"
              - $ref: "#/components/schemas/EvalPythonGrader"
              - $ref: "#/components/schemas/EvalScoreModelGrader"

The property is of array type, and the array could contain one of the nominated types. So what is default value "eval"?

[zijianhuang]

supposedly the property can be use to generated in strongly typed language like C#:

public object[] Testing_criteria { get; set; }

Or TypeScript

Testing_criteria : Array<EvalLabelModelGrader | EvalStringCheckGrader ...>