def invalid_json_schema():
    """
    Verified 2015-06-16 for creating a LB, changing a node, adding nodes:

    - when providing invalid fields in the JSON request
    - when providing invalid JSON
    - this schema validation happens even before checking whether a LB and/or
      node exists

    :return: a `tuple` of (dict body message, 400 http status code)
    """
    return {'message': ['JSON does not match the expected schema']}, 400
