The date and time to be used as signature metadata. This value should be
a Date object, a unix (epoch) timestamp, or a string that can be
understood by the JavaScript Date constructor.If not supplied, the
value returned by new Date() will be used.
The region name to sign the request. It will override the signing region of the signer in current invocation
The service signing name. It will override the service name of the signer in current invocation