def set_iscsi_discovery_auth(
        client,
        disable_chap=None,
        require_chap=None,
        mutual_chap=None,
        chap_group=None):
    """Set CHAP authentication for discovery service.

    Args:
        disable_chap: CHAP for discovery session should be disabled (optional)
        require_chap: CHAP for discovery session should be required (optional)
        mutual_chap: CHAP for discovery session should be mutual (optional)
        chap_group: Authentication group ID for discovery session (optional)

    Returns:
        True or False
    """
    params = {}

    if disable_chap:
        params['disable_chap'] = disable_chap
    if require_chap:
        params['require_chap'] = require_chap
    if mutual_chap:
        params['mutual_chap'] = mutual_chap
    if chap_group:
        params['chap_group'] = chap_group

    return client.call('set_iscsi_discovery_auth', params)