def normalize_json_fields(result_list):
    """
        Makes sure that each json contains the same fields.
        Adds them with None as value if any field is missing.
    """

    found_keys = set()
    for item in result_list:
        found_keys.update(item.keys())

    for item in result_list:
        for key in found_keys:
            if key not in item:
                item[key] = None

    return result_list