Authentication

Authenticate	Called with the URL of a request and return the HTTP headers necessary to authenticate it.
BasicAuthentication	Authenticate requests with basic authentication.
ClientCertificate	A client certificate to connect() to a session configured with ClientCertificateConfig.
OAuth2ResourceOwnerPasswordAuthentication	Authenticate requests with OAuth 2's Resource Owner Password Credentials Grant.
TokenAuthentication	Authenticate requests by passing the given token in the Authorization header.