Retrieve all the DNS entries of the Subject Alternative Name extension.

def get_dns_subject_alternative_names(certificate: cryptography.x509.Certificate) -> List[str]:
        """Retrieve all the DNS entries of the Subject Alternative Name extension.
        """
        subj_alt_names: List[str] = []
        try:
            san_ext = certificate.extensions.get_extension_for_oid(ExtensionOID.SUBJECT_ALTERNATIVE_NAME)
            subj_alt_names = san_ext.value.get_values_for_type(DNSName)
        except ExtensionNotFound:
            pass
        return subj_alt_names