public void validate(Map<String, NewDocumentType> documentDefinitions) {
        List<String> conflictingNames = documentDefinitions.keySet().stream()
                .filter(this::isReservedName)
                .toList();
        if (!conflictingNames.isEmpty()) {
            throw new IllegalArgumentException(makeReservedNameMessage(conflictingNames));
        }
    }
@Test
    void exception_is_not_thrown_on_unreserved_name() {
        ReservedDocumentTypeNameValidator validator = new ReservedDocumentTypeNameValidator();
        validator.validate(asDocTypeMapping(List.of("foo")));
    }