Bug 28510 java build path inconsistency [build path]
20021216 select rt.jar in the package explorer open properties it allows you to set the javadoc location but for source attachment you are sent somewhere else it's inconsistent - on the java build path they both look sort of the same (they sit under the same node in the tree)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
boolean projectExists= false;
		List newClassPath= null;
		try {
			IProject project= fCurrJProject.getProject();
			projectExists= (project.exists() && project.getFile(".classpath").exists()); 
			if  (projectExists) {
				if (outputLocation == null) {
					outputLocation=  fCurrJProject.getOutputLocation();
				}
				if (classpathEntries == null) {
					classpathEntries=  fCurrJProject.getRawClasspath();
				}
			}
			if (outputLocation == null) {
				outputLocation= getDefaultBuildPath(jproject);
			}			
			if (classpathEntries != null) {
				newClassPath= getExistingEntries(classpathEntries);
			}
		} catch (CoreException e) {
			JavaPlugin.log(e);
		}
		if (newClassPath == null) {
			newClassPath= getDefaultClassPath(jproject);
		}
		
		List exportedEntries = new ArrayList();
		for (int i= 0; i < newClassPath.size(); i++) {
			CPListElement curr= (CPListElement) newClassPath.get(i);
			if (curr.isExported() || curr.getEntryKind() == IClasspathEntry.CPE_SOURCE) {