fix: handle required in oneOf so samples match a single alternative

[cpruijsen]

What/Why/How?

The sampler now lifts the selected oneOf alternative's required onto the parent so skipNonRequired can see it, and omits properties that are required only by sibling alternatives so the example matches exactly one subschema: { "a": "string" }. It still selects the first oneOf.

oneOf alternatives that only set required were ignored when building the parent object sample. For

{
  "type": "object",
  "properties": {
    "a": { "type": "string" },
    "b": { "type": "string" }
  },
  "oneOf": [
    { "required": ["a"] },
    { "required": ["b"] }
  ]
}

the sampler emitted { "a": "string", "b": "string" }, which matches both alternatives (must match exactly one schema in oneOf). { skipNonRequired: true } produced {}, which matches none.

Other optional parent properties stay, matching the default "sample all properties" behaviour. The invalid sample was exclusivity (a and b together match two branches), not extra optional fields.

Emitting only the selected required keys (implied skipNonRequired under oneOf) would also drop unrelated optional properties such as c. Happy to switch to selected required keys only if you prefer smaller examples.

required is read from the alternative object itself (the reporter's schema). $ref / nested allOf on a oneOf item is unchanged.

Closes #151.

Reference

#151

Testing

• Reporter schema: default sample is { a: "string" }
• Same schema with skipNonRequired: true is { a: "string" }, not {}
• Unrelated optional parent properties are still sampled
• Existing oneOf / anyOf / discriminator tests still pass
• Those new tests fail without the source change and pass with it

Screenshots (optional)

N/A

Check yourself

• Code is linted
• Tested
• All new/updated code is covered with tests

Security

• Security impact of change has been considered
• Code follows company security practices and guidelines