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
if (!result.isOK()) {
			setErrorMessage(result.getMessage());
			return false;
		}
		IStatus linkedResourceStatus = null;
		if (valid) {
			linkedResourceStatus = validateLinkedResource();
			if (linkedResourceStatus.getSeverity() == IStatus.ERROR) {
				valid = false;
			}
		}
		
		if (valid
				&& (linkedResourceStatus == null || linkedResourceStatus.isOK())) {
			setMessage(null);
			setErrorMessage(null);
		}
		return valid;
	}
	/*
	 * @see DialogPage.setVisible(boolean)
	 */
	public void setVisible(boolean visible) {
		super.setVisible(visible);
		if (visible) {
			resourceGroup.setFocus();
		}
	}
}