Changes are only applied when readOnly=false is explicit

[FerroEduardo]

Although @Transactional default value of readOnly is false, the method update() only make changes when explicitly defining the property. Am I doing something wrong or this is a bug?

@Singleton
@Transactional(readOnly = true)
public class TodoService {

    [...]

    public List<Todo> index() {
        return repository.findAll();
    }

    @Transactional
    public Todo create(String description) {
        Todo todo = new Todo(null, description, Boolean.FALSE);

        return repository.save(todo);
    }

    @Transactional(readOnly = false)
    public Todo update(Long id, String description, Boolean completed) {
        Optional<Todo> optionalTodo = repository.findById(id);
        if (optionalTodo.isEmpty()) {
            throw new NotFoundException();
        }
        Todo todo = optionalTodo.get();
        todo.setDescription(description);
        if (completed != null) {
            todo.setCompleted(completed);
        }

        return repository.save(todo);
    }
}

Source code: https://github.com/FerroEduardo/micronaut-todo
Test: https://github.com/FerroEduardo/micronaut-todo/blob/main/src/test/java/com/ferroeduardo/TodoTest.java#L86-L102
JUnit report: https://github.com/FerroEduardo/micronaut-todo/actions/runs/6774044816