fix: null values in examples, example and default (#4339, #4229) by ewaostrowska · Pull Request #5060 · swagger-api/swagger-core (original) (raw)

This pull request enhances how OpenAPI 3.1 Schema objects handle and serialize null and literal "null" values for default, example, and examples fields. The changes ensure correct distinction between a missing field, an explicit null, and the string "null", especially when nullable=true. This improves both the internal model and the generated OpenAPI output, and aligns the code with the OpenAPI 3.1 specification.

Key changes:

Handling of null and "null" values for default and example:

• Updated ModelResolver and AnnotationsUtils to interpret the string "null" as a Java null only when nullable=true; otherwise, "null" is treated as a literal string. This logic is applied for both defaultValue and example attributes.
• Added a new defaultSetFlag to the Schema model to track when the default value is explicitly set to null (vs. not set at all), mirroring the existing exampleSetFlag.

Serialization improvements:

• Modified SchemaSerializer and Schema31Serializer to ensure that if example or default is explicitly set to null, the serialized JSON includes "example": null or "default": null fields, rather than omitting them.
  Consistent parsing and handling of examples arrays:
• Added a new utility method parseExamplesArray to parse each entry in the examples array, converting "null" to null when appropriate, and returning parsed JSON objects/arrays or the original string as needed.
• Updated all relevant code paths to use this method for setting the examples property, and ensured this logic is only applied for OpenAPI 3.1.

These changes improve the fidelity of OpenAPI schema generation and serialization, especially regarding explicit null handling and the distinction from the literal string "null".

Should fix: #4339 , #4229, #4401