feat: add PoC of handling discriminator for oneOf/anyOf cases in OpenAPI 3.1

[glowcloud]

Notes on the idea of handling discriminator:

Dereference: dereference value of MemberElement contained within Discriminator.mapping and set the result as its metadata.

discriminator:
   propertyName: petType
   mapping:
      dog: Dog # => should be dereferenced and the dereference result should be set as metadata

Normalization: compare oneOf/anyOf items with the mapping values metadata and create normalized mapping based on the result:

• If both oneOf and anyOf are present, do not normalize
• Compare external references and internal references that do not point to components/schema/<schemaName>:
  • These references will be recognized by having a different baseURI or by not having schemaName metadata.
  • The comparison is done based on $refBaseURI metadata.
  • If no mapping exists, normalization will not be successful.
• Compare internal references that point to components/schema/<schemaName>:
  • These references will be recognized by having schemaName metadata.
  • The comparison is done based on schemaName and $refBaseURI metadata.
  • If no mapping exists, create it as <schemaName>: <schema>.
• If normalization was successful, set the normalized mapping to a Specification Extension field (e.g. x-normalized-mapping)

Additionally, we should have a new strategy option to check if we should dereference Discriminator.mapping values.

[robert-hebel-sb]

won't passing an undefined parent cause a type error?

[robert-hebel-sb]

Suggested change

	let normalizationResult = true;
	let hasNormalizationResult = true;

[robert-hebel-sb]

Maybe we should check before whether storage is not being empty?

[robert-hebel-sb]

Suggested change

	const items = isArrayElement(schemaElement.oneOf)
	? schemaElement.oneOf
	: schemaElement.anyOf;
	items!.forEach((item) => {
	if (!isSchemaElement(item)) {
	return;
	}
	const items = isArrayElement(schemaElement.oneOf)
	? schemaElement.oneOf
	: (schemaElement.anyOf as ArrayElement);
	items.forEach((item) => {
	if (!isSchemaElement(item)) {
	return;
	}