def has_valid_custom_headers(custom_headers: list):
    """
    Check if the list of custom header is valid
    :param custom_headers: list of CustomHeader to validate
    :type custom_headers: list
    :return the result
     :rtype bool
    """
    if custom_headers is None:
        return True
    for item in custom_headers:
        valid = item.isvalid()
        if valid is False:
            return False
    return True