Hm, I see them published for spring-web and also spring-web-reactive. The class you have clicked on in the attached image is actually an existing class in the spring-web module which itself is an existing so I don't think this is related to the build. Could there be some issue in the local maven repository or IDE related ?
Interestingly, it looks like I pulled the sources of Spring 5 July 13th, a date when the reactive support hadn't been merged back yet. The intermediate binary updates issued by the IDE didn't pull down the sources again. I now manually triggered the download of sources and they're now showing up properly.