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
return new CPListElement[] { new CPListElement(fCurrJProject, IClasspathEntry.CPE_LIBRARY, configured, null) };
			}
		}		
		return null;
	}
		
	private CPListElement[] openVariableSelectionDialog(CPListElement existing) {
		List existingElements= fLibrariesList.getElements();
		ArrayList existingPaths= new ArrayList(existingElements.size());
		for (int i= 0; i < existingElements.size(); i++) {
			CPListElement elem= (CPListElement) existingElements.get(i);
			if (elem.getEntryKind() == IClasspathEntry.CPE_VARIABLE) {
				existingPaths.add(elem.getPath());
			}
		}
		IPath[] existingPathsArray= (IPath[]) existingPaths.toArray(new IPath[existingPaths.size()]);
		
		if (existing == null) {
			IPath[] paths= BuildPathDialogAccess.chooseVariableEntries(getShell(), existingPathsArray);
			if (paths != null) {
				ArrayList result= new ArrayList();
				for (int i = 0; i < paths.length; i++) {
					CPListElement elem= new CPListElement(fCurrJProject, IClasspathEntry.CPE_VARIABLE, paths[i], null);
					IPath resolvedPath= JavaCore.getResolvedVariablePath(paths[i]);
					elem.setIsMissing((resolvedPath == null) || !resolvedPath.toFile().exists());
					if (!existingElements.contains(elem)) {
						result.add(elem);
					}
				}
				return (CPListElement[]) result.toArray(new CPListElement[result.size()]);