Private interface methods, example use-case?

Question

\"Support for private methods in interfaces was briefly in consideration for inclusion in Java SE 8 as part of the effort to add support for Lambda Expressions, but was with

Answer 1

Why not simply (simply = using Java8):

PS: because of private helper is not possible in Java

public interface MyInterface {
 private static class Helper{
     static initializeMyClass(MyClass myClass, Params params){
         //do magical things in 100 lines of code to initialize myClass for example
     }
 }

 default MyClass createMyClass(Params params) {
     MyClass myClass = new MyClass();
     Helper.initializeMyClass(myClass, params);
     return myClass;
 }

 default MyClass createMyClass() {
     MyClass myClass = new MyClass();
     Helper.initializeMyClass(myClass, null);
     return myClass;
 }
}