Add Maven nature to existing Eclipse project that has pom but no Maven submenu

Delete the project (but do not delete it from disk) and re-import but choose to import an existing Maven project.

I had the same issue. I do not even have the configure option as mentioned in the accepted answer. But as @captain said i deleted them, But importing as maven doesn't work either. So I tried the other option below.

Instead of importing as Existing maven project I imported them as General -> Projects from folder or Archive.

This brought back maven nature and boot nature as well.

Right click on the project- Configure - Convert -Convert to Maven Project

This is also a method to refresh the Maven Dependencies.

In the latest IDE's it is this way: right click on project >> Configure >> Convert to Maven Project