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/SourceContainerWorkbookPage.java
if (fFoldersList.getIndexOfElement(elem) != -1) {
			editElementEntry((CPListElement) elem);
		} else if (elem instanceof CPListElementAttribute) {
			editAttributeEntry((CPListElementAttribute) elem);
		}
	}
	private void editElementEntry(CPListElement elem) {
		CPListElement res= null;
		
		IResource resource= elem.getResource();
		if (resource.exists()) {
			CPListElement[] arr= openSourceContainerDialog(elem);
			if (arr != null) {
				res= arr[0];
			}
		} else {
			res= openNewSourceContainerDialog(elem);
		}
		
		if (res != null) {
			fFoldersList.replaceElement(elem, res);
		}
	}
	private void editAttributeEntry(CPListElementAttribute elem) {
		String key= elem.getKey();
		if (key.equals(CPListElement.OUTPUT)) {
			CPListElement selElement= (CPListElement) elem.getParent();
			OutputLocationDialog dialog= new OutputLocationDialog(getShell(), selElement);
			if (dialog.open() == OutputLocationDialog.OK) {
				selElement.setAttribute(CPListElement.OUTPUT, dialog.getOutputLocation());