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 void run() {
					setupBasedOnInitialSelections();
				}
			});
		setControl(composite);
		update();
		giveFocusToDestination();
		
		WorkbenchHelp.setHelp(composite, IJavaHelpContextIds.JARPACKAGER_WIZARD_PAGE);
	}
	/**
	 *	Create the export options specification widgets.
	 *
	 *	@param parent org.eclipse.swt.widgets.Composite
	 */
	protected void createOptionsGroup(Composite parent) {
		Composite optionsGroup= new Composite(parent, SWT.NONE);
		GridLayout layout= new GridLayout();
		layout.marginHeight= 0;
		optionsGroup.setLayout(layout);
		fCompressCheckbox= new Button(optionsGroup, SWT.CHECK | SWT.LEFT);
		fCompressCheckbox.setText(JarPackagerMessages.getString("JarPackageWizardPage.compress.text")); 
		fCompressCheckbox.addListener(SWT.Selection, this);
		fOverwriteCheckbox= new Button(optionsGroup, SWT.CHECK | SWT.LEFT);
		fOverwriteCheckbox.setText(JarPackagerMessages.getString("JarPackageWizardPage.overwrite.text")); 
		fOverwriteCheckbox.addListener(SWT.Selection, this);
	}
	/**
	 *	Answer the contents of the destination specification widget. If this
	 *	value does not have the required suffix then add it first.