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
IRunnableWithProgress op = new IRunnableWithProgress() {
			public void run(IProgressMonitor monitor) {
				CreateFileOperation op = new CreateFileOperation(newFileHandle,
						linkTargetPath, initialContents,
						IDEWorkbenchMessages.WizardNewFileCreationPage_title);
				try {
					PlatformUI.getWorkbench().getOperationSupport()
							.getOperationHistory().execute(
									op,
									monitor,
									WorkspaceUndoUtil
											.getUIInfoAdapter(getShell()));
				} catch (final ExecutionException e) {
					getContainer().getShell().getDisplay().syncExec(
							new Runnable() {
								public void run() {
									if (e.getCause() instanceof CoreException) {
										ErrorDialog
												.openError(
														getContainer()
																.getShell(), 
														
														IDEWorkbenchMessages.WizardNewFileCreationPage_errorTitle,
														null, 
														
														((CoreException) e
																.getCause())
																.getStatus());
									} else {
										IDEWorkbenchPlugin