"unknown option" warnings at config creation

During swift_proxy_server start the following warnings are reported:

2021-03-18T07:56:05.298678000Z swift-proxy-server: STDERR: The option "bind_ip" is not known to keystonemiddleware
2021-03-18T07:56:05.298932000Z swift-proxy-server: STDERR: The option "bind_port" is not known to keystonemiddleware
2021-03-18T07:56:05.299332000Z swift-proxy-server: STDERR: The option "log_udp_host" is not known to keystonemiddleware
2021-03-18T07:56:05.299739000Z swift-proxy-server: STDERR: The option "log_udp_port" is not known to keystonemiddleware
2021-03-18T07:56:05.300058000Z swift-proxy-server: STDERR: The option "log_name" is not known to keystonemiddleware
2021-03-18T07:56:05.300452000Z swift-proxy-server: STDERR: The option "log_facility" is not known to keystonemiddleware
2021-03-18T07:56:05.300836000Z swift-proxy-server: STDERR: The option "log_level" is not known to keystonemiddleware
2021-03-18T07:56:05.301203000Z swift-proxy-server: STDERR: The option "workers" is not known to keystonemiddleware
2021-03-18T07:56:05.301604000Z swift-proxy-server: STDERR: The option "auth_url" is not known to keystonemiddleware
2021-03-18T07:56:05.301985000Z swift-proxy-server: STDERR: The option "project_domain_id" is not known to keystonemiddleware
2021-03-18T07:56:05.302495000Z swift-proxy-server: STDERR: The option "user_domain_id" is not known to keystonemiddleware
2021-03-18T07:56:05.302893000Z swift-proxy-server: STDERR: The option "project_name" is not known to keystonemiddleware
2021-03-18T07:56:05.303346000Z swift-proxy-server: STDERR: The option "username" is not known to keystonemiddleware
2021-03-18T07:56:05.303794000Z swift-proxy-server: STDERR: The option "password" is not known to keystonemiddleware
2021-03-18T07:56:05.304538000Z swift-proxy-server: STDERR: The option "__name__" is not known to keystonemiddleware

At keystonemiddleware initialisation, swift_proxy_server provides configuration options from proxy-server.conf. Provided options are from groups [DEFAULT], [filter:authtoken] and [filter:keystoneauth].
At the init of keystonemiddleware, validation of all config options is executed in the following function:

def _conf_values_type_convert(group_name, all_options, conf):
    """Convert conf values into correct type."""
    if not conf:
        return {}

    opts = {}
    opt_types = {}

    for group, options in all_options:
        # only accept paste overrides for the primary group
        if group != group_name:
            continue

        for o in options:
            type_dest = (getattr(o, 'type', str), o.dest)
            opt_types[o.dest] = type_dest
            # Also add the deprecated name with the same type and dest.
            for d_o in o.deprecated_opts:
                opt_types[d_o.name] = type_dest

        break

    for k, v in conf.items():
        dest = k
        try:
            if v is not None:
                type_, dest = opt_types[k]
                v = type_(v)
        except KeyError: # nosec
            # This option is not known to auth_token. v is not converted.
            _LOG.warning(
                'The option "%s" in conf is not known to auth_token', k)
        except ValueError as e:
            raise exceptions.ConfigurationError(
                _('Unable to convert the value of %(key)s option into correct '
                  'type: %(ex)s') % {'key': k, 'ex': e})
        opts[dest] = v

    return opts

In function, there's a validation of whether the passed option is present in supported options. This validation fails on all options from swift proxy server [DEFAULT] configuration section and on all options relevant to keystoneauth1 plugin type "password" from [filter:authtoken].

These warnings have no impact on functionality of swift_proxy_server or keystonemiddleware itself.