Actually is it mandatory that dependent libs should be in .class? Even if those are in .java, compiler will make .class files in the build folder know.
If you want it to run yes. The source jar is useful if you want to be able to be able to open a class in your
IDE and view the source. The sources are also needed to build the project if you wanted to make changes to the framework classes. If you wanted to do that you would follow the instructions here:
http://blog.springsource.org/2009/03/03/building-spring-3/
After building Spring from the source contained in that jar you would end up with exactly the same jar I had linked to in my last post.
Simply including a jar containing source files does not mean your IDE is going to automatically compile them for you. Think of a jar file as similar to a zip.
But why shouldn't the spring distribution comes with .class version of all jars needed as it comes with sources with all jars needed.
I have been using Maven so truthfully had not downloaded it from their website. I did so now and peeked in it. in the src folder you have all the source jars. In the dist folder you have all the compiled jars. Use the jars in the dist folder.