Bug 172000 [Wizards] WizardNewFileCreationPage should support overwriting existing resources
In the WizardNewFileCreationPage, there should be a method to set allowExistingResources flag for ResourceAndContainerGroup member. It is useful when both "create" and "renew/overwrite" operations are meaningful for a wizard.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/WizardNewFileCreationPage.java
* <p>
	 * Subclasses may reimplement.
	 * </p>
	 * 
	 * @return the label to display in the file name specification visual
	 *         component group
	 */
	protected String getNewFileLabel() {
		return IDEWorkbenchMessages.WizardNewFileCreationPage_fileLabel;
	}
	/**
	 * Shows/hides the advanced option widgets.
	 */
	protected void handleAdvancedButtonSelect() {
		Shell shell = getShell();
		Point shellSize = shell.getSize();
		Composite composite = (Composite) getControl();
		if (linkedResourceComposite != null) {
			linkedResourceComposite.dispose();
			linkedResourceComposite = null;
			composite.layout();
			shell.setSize(shellSize.x, shellSize.y - linkedResourceGroupHeight);
			advancedButton.setText(IDEWorkbenchMessages.showAdvanced);
		} else {
			linkedResourceComposite = linkedResourceGroup
					.createContents(linkedResourceParent);
			if (linkedResourceGroupHeight == -1) {
				Point groupSize = linkedResourceComposite.computeSize(
						SWT.DEFAULT, SWT.DEFAULT, true);
				linkedResourceGroupHeight = groupSize.y;