Require client to present authentication, if not presented then negotiations will be declined.

- `Anything`
  - `Object`
    - `Basic` ...and other supertypes
      - `ClientAuth`
        - `required`

- `required`
  - `ClientAuth`
    - `Basic`
      - `Identifiable`
      - `Object`
        - `Anything`

no subtypes hierarchy

Inherited Attributes
Attributes inherited from: `ClientAuth` `name`
Attributes inherited from: `Object` `hash`, `string`

Inherited Methods
Methods inherited from: `Object` `equals`