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
if (!project.isOpen()) {
				project.open(monitor);
				monitor= null;
			}
		} finally {
			if (monitor != null) {
				monitor.done();
			}
		}
	}
	public static void addJavaNature(IProject project, IProgressMonitor monitor) throws CoreException {
		if (!project.hasNature(JavaCore.NATURE_ID)) {
			IProjectDescription description = project.getDescription();
			String[] prevNatures= description.getNatureIds();
			String[] newNatures= new String[prevNatures.length + 1];
			System.arraycopy(prevNatures, 0, newNatures, 0, prevNatures.length);
			newNatures[prevNatures.length]= JavaCore.NATURE_ID;
			description.setNatureIds(newNatures);
			project.setDescription(description, monitor);
		} else {
			monitor.worked(1);
		}
	}
	
	public void configureJavaProject(IProgressMonitor monitor) throws CoreException, InterruptedException {
		if (monitor == null) {
			monitor= new NullProgressMonitor();
		}				
		monitor.beginTask(NewWizardMessages.getString("BuildPathsBlock.operationdesc_java"), 10); 
		try {