Bug 64298 JAR files already in build path still shown when adding JARs.
When adding JARs to the Java build path in 3.0M9, the JAR's that are already added do not get filtered out anymore like with all previous builds (M8 and lower). Instead, the complete list of all available JARs is shown.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/LibrariesWorkbookPage.java
fLibrariesList= new TreeListDialogField(adapter, buttonLabels, new CPListLabelProvider());
		fLibrariesList.setDialogFieldListener(adapter);
		fLibrariesList.setLabelText(NewWizardMessages.getString("LibrariesWorkbookPage.libraries.label")); 
		fLibrariesList.enableButton(IDX_REMOVE, false);
		fLibrariesList.enableButton(IDX_EDIT, false);
		
		fLibrariesList.setViewerSorter(new CPListElementSorter());
	}
		
	public void init(IJavaProject jproject) {
		fCurrJProject= jproject;
		updateLibrariesList();
	}
	
	
	private void updateLibrariesList() {
		List cpelements= fClassPathList.getElements();
		List libelements= new ArrayList(cpelements.size());
		
		int nElements= cpelements.size();
		for (int i= 0; i < nElements; i++) {
			CPListElement cpe= (CPListElement)cpelements.get(i);
			if (isEntryKind(cpe.getEntryKind())) {
				libelements.add(cpe);
			}
		}
		fLibrariesList.setElements(libelements);
	}