Get the configuration settings associated to a list of schema
    interfaces

    :param iface: The schema interface from which we want to get its
    fields
    :return: Dictionary with iface name as key and as value a dictionary
    with the setting names (keys) linked to that schema and its
    values.

def get_settings_from_interface(iface):
    """Get the configuration settings associated to a list of schema
    interfaces

    :param iface: The schema interface from which we want to get its
    fields
    :return: Dictionary with iface name as key and as value a dictionary
    with the setting names (keys) linked to that schema and its
    values.
    """
    settings = {}
    schema_id = iface.getName()
    settings[schema_id] = {}
    schema = getAdapter(api.get_portal(), iface)
    for setting in getFieldNames(iface):
        value = getattr(schema, setting, None)
        if is_json_serializable(value):
            settings[schema_id][setting] = value
    return settings