Resources

Hello,

I tried to use the resources on the basis of the book (https://vaadin.com/book/-/page/application.resources.html) but I can not find any of the three classes “FileResouce, StreamResource and ClassResource” in eclipse. I always get the message “Stream resource can not be resolved to a type” and I do not find the import?
How can this be?

Thanks in advance
danny

Update: After I reinstalled eclipse, it worked. Strange problem…