metrics-server/vendor/k8s.io/kube-openapi/pkg/generators/README

# Generate OpenAPI definitions

- To generate definition for a specific type or package add "+k8s:openapi-gen=true" tag to the type/package comment lines.
- To exclude a type or a member from a tagged package/type, add "+k8s:openapi-gen=false" tag to the comment lines.

# OpenAPI Extensions
OpenAPI spec can have extensions on types. To define one or more extensions on a type or its member
add `+k8s:openapi-gen=x-kubernetes-$NAME:`$VALUE`` to the comment lines before type/member. A type/member can
have multiple extensions. The rest of the line in the comment will be used as $VALUE so there is no need to
escape or quote the value string. Extensions can be used to pass more information to client generators or
documentation generators. For example a type might have a friendly name to be displayed in documentation or
being used in a client's fluent interface.

# Custom OpenAPI type definitions

Custom types which otherwise don't map directly to OpenAPI can override their
OpenAPI definition by implementing a function named "OpenAPIDefinition" with
the following signature:

	import openapi "k8s.io/kube-openapi/pkg/common"

	// ...

	type Time struct {
		time.Time
	}

	func (_ Time) OpenAPIDefinition() openapi.OpenAPIDefinition {
		return openapi.OpenAPIDefinition{
			Schema: spec.Schema{
				SchemaProps: spec.SchemaProps{
					Type:   []string{"string"},
					Format: "date-time",
				},
			},
		}
	}

Alternatively, the type can avoid the "openapi" import by defining the following
methods. The following example produces the same OpenAPI definition as the
example above:

    func (_ Time) OpenAPISchemaType() []string { return []string{"string"} }
    func (_ Time) OpenAPISchemaFormat() string { return "date-time" }

TODO(mehdy): Make k8s:openapi-gen a parameter to the generator now that OpenAPI has its own repo.