oas2PolymorphicAnyOf will check a specification to ensure that if it’s a Swagger specification (OpenAPI 2.0), then
it has not made use of anyOf.
Example ruleset configuration
oas2-anyOf: description: "Check for invalid use of 'anyOf'" type: "validation" recommended: true severity: "err" given: "$" then: function: "oas2PolymorphicAnyOf"
The function is used by the oas2-anyOf Rule