.forEach(s -> messages.addErrorsPropertyRequired(s, s)));
            }

            if (!fessConfig.validateIndexArrayFields(doc)) {
                throwError.accept(messages -> fessConfig.invalidIndexArrayFields(doc)
                        .stream()
                        .map(s -> "doc." + s)
                        .forEach(s -> messages.addErrorsPropertyRequired(s, s)));
            }

        }
        return fieldSet;
    }

    default boolean validateIndexArrayFields(final Map<String, Object> source) {
        return invalidIndexArrayFields(source).isEmpty();
    }

    default List<String> invalidIndexArrayFields(final Map<String, Object> source) {
        // TODO always returns empty list