En Java 9, quels types de variables/méthodes sont définis dans les interfaces ?

import java.util.*;
import java.util.stream.*;
interface InterfaceTest {
   static void printEvenNumbers() {
      getDataStream().<strong>filter</strong>(i -> i%2==0).<strong>forEach</strong>(System.out::println);
   }
   static void printLOddNumbers() {
      getDataStream().<strong>filter</strong>(i -> i%2!=0).<strong>forEach</strong>(System.out::println);
   }
   <strong>private </strong><strong>static </strong>Stream<Integer> getDataStream() {       <strong>// private static method</strong>
      <strong>List<Integer></strong> list = Arrays.asList(10, 13, 5, 15, 12, 20, 11, 25, 16);
      return list.stream();
   }
}
public class InterfacePrivateMethodTest implements InterfaceTest {
   public static void main(String args[]) {
      System.out.println("The even numbers: ");
      InterfaceTest.<strong>printEvenNumbers()</strong>;
      System.out.println("The odd numbers: ");
      InterfaceTest.<strong>printLOddNumbers()</strong>;
   }
}

<strong>The even numbers:
10
12
20
16
The odd numbers:
13
5
15
11
25</strong>