configuration.go
func IssuingCertificateURL(value ...string) Option {
	return func(c *configuration) {
		c.issuingCertificateURL = append(c.issuingCertificateURL, value...)
	}
}
func IssuingCertificateURL(value ...string) Option {
	return func(c *configuration) {
		c.issuingCertificateURL = append(c.issuingCertificateURL, value...)
	}
}
// IssuingCertificateURL is an Option for setting the identity's certificate's
// IssuingCertificateURL.