Brincando um pouco com Lambda Function no Java

Lambda.java

import java.util.List;
import java.util.ArrayList;

//This interface apply a pre-condition
interface Predicate<T>{
    boolean test(T t);
}

//This interface apply a modification on element 
interface Function<E, S> {
    S apply(E e); 
}

public Lambda Teste {
    public static void main(String args[]) {
       List<String> lista = new ArrayList<>();
       lista.add("Lucas");
       lista.add("Zezim");
       lista.add("Morpheu");

       printString(lista, t -> t.equals("Lucas") );

       printString(lista, t -> {
                return t.equals("Morpheu");
            }
       );
       
       List<String> modified = applicator(lista, p -> p + "s");

       for(String word : modified) {
            System.out.println(word);
       }
        
    }

    public static void printString(List<String> a, Predicate<String> tester) {
        for(String word : a) {
            if(tester.test(word)) {
                System.out.println(word);
            }
        }
    }

    public static List<String> applicator(List<String> a, Function<String, String> function) {
        List<String> b = new ArrayList<>();
        for(String word : a) {
            b.add(function.apply(word));
        }
        return b;
    }
}