Bug 31556 Export jar from Navigator view fails
(M5 build) In Navigator view (resource perspective), right-click on a src/ directory containing your sources, select export->jar file and the package selector opens with no resource selected (and finish button disabled); but it seems that the src/ dir is really selected, because if you re-select it in the window, it ends up with a "jar creation failed" and a lot of duplicate entries in the error log. If you try the same from the Projects view (Java browsing perspective), it works fine.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarPackageWizardPage.java
public JarPackageWizardPage(JarPackageData jarPackage, IStructuredSelection selection) {
		super(PAGE_NAME, selection);
		setTitle(JarPackagerMessages.getString("JarPackageWizardPage.title")); 
		setDescription(JarPackagerMessages.getString("JarPackageWizardPage.description")); 
		fJarPackage= jarPackage;
		fInitialSelection= selection;
	}
	/*
	 * Method declared on IDialogPage.
	 */
	public void createControl(final Composite parent) {
		
		initializeDialogUnits(parent);
		
		Composite composite= new Composite(parent, SWT.NULL);
		composite.setLayout(new GridLayout());
		composite.setLayoutData(
			new GridData(GridData.VERTICAL_ALIGN_FILL | GridData.HORIZONTAL_ALIGN_FILL));
		createPlainLabel(composite, JarPackagerMessages.getString("JarPackageWizardPage.whatToExport.label")); 
		createInputGroup(composite);
		createExportTypeGroup(composite);
		new Label(composite, SWT.NONE); 
		createPlainLabel(composite, JarPackagerMessages.getString("JarPackageWizardPage.whereToExport.label")); 
		createDestinationGroup(composite);
		createPlainLabel(composite, JarPackagerMessages.getString("JarPackageWizardPage.options.label")); 
		createOptionsGroup(composite);
		restoreResourceSpecificationWidgetValues(); 
		restoreWidgetValues();
		if (fInitialSelection != null)
			BusyIndicator.showWhile(parent.getDisplay(), new Runnable() {