t :: %Dnsimple.Certificate{authority_identifier: String.t, chain: String.t, common_name: String.t, created_at: String.t, csr: String.t, domain_id: integer, expires_on: String.t, id: integer, name: String.t, private_key: String.t, root: String.t, server: String.t, state: String.t, updated_at: String.t, years: integer}