René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Nullable `allOf`s with default `null` values fail validation","articleBody":"Hi,\n\nIn OpenAPI 3.0 it's a common pattern to represent a reference that can be null as an `allOf` with `nullable: true`. \n\nHowever, if you set the `default` to `null`, `openapi-spec-validator` attempts to validate `null` against the referenced schema, and returns an error. The default should take into account the nullability of the schema that it's part of, not just the referenced `allOf`.\n\n```\n{\n  \"info\": {\n    \"title\": \"Example\",\n    \"version\": \"v1\",\n  },\n  \"openapi\": \"3.0.2\",\n  \"components\": {\n    \"schemas\": {\n      \"FooSchema\": {\n        \"title\": \"FooSchema\",\n        \"type\": \"object\"\n      },\n      \"BarSchema\": {\n        \"allOf\": [\n          {\n            \"$ref\": \"#/components/schemas/FooSchema\"\n          }\n        ],\n        \"nullable\": true,\n        \"default\": null\n      }\n    }\n  },\n  \"paths\": {}\n}\n```\n\n```\nFailed validating 'type' in schema['allOf'][0]:\n    {'title': 'FooSchema', 'type': 'object'}\n\nOn instance:\n    None\n```","author":{"url":"https://github.com/pranjalv123","@type":"Person","name":"pranjalv123"},"datePublished":"2025-07-01T13:33:20.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/418/openapi-spec-validator/issues/418"}