Des erreurs de programmation java ou mauvaises pratiques

public class CustomerRepository {
	private static  CustomerRepository INSTANCE = null;
	private CustomerRepository(){}
	
	private static void createInstance() {
		if (INSTANCE == null) {
			INSTANCE = new CustomerRepository();
		}
	}
	public static CustomerRepository getInstance() {
		if (INSTANCE == null) createInstance();
		return INSTANCE;
	}
		
}