I checked out the existing project source code from SVN to a folder in my system.
Then I opened eclipse. Import Project-> Existing Maven Project.
It imported without issues. However, Project Explorer shows it as just folders instead of packages. (Like when we create a package and then add classes to it, it shows a different icon for package root). I opened Navigator and Package Explorer as well. But they are showing them as folders as well.
---- Edit ----
If this doesnt work, it is likely that someone checked in their environment files into your SVN. If they checked in:
They could be conflicting with your environment (different settings/plugins/versions of eclipse...). Try dropping your project, deleting the folder/files, then remove these files from SVN, and repeat your initial process. All of these files/folders will get generated during the import to eclipse.
---- Edit 2 ----
Per your recent edit to the question, you have a multi-module project. If you only did this on the parent project, then there is no source folder. So you wouldn't see it. You should:
In eclipse, each module of a multi-module maven project needs its own eclipse project.