JDK8 example: implementing an empty Iterable<Object> (functional interface with default method) with a lambda expression.

LambdaIterable.java

interface java.lang.Iterable<T> {
  abstract Iterator<T> iterator();

  default void forEach(Consumer<? super T> consumer) {
    for (T t : this) {
      consumer.accept(t);
    }
  }
}

java.lang.Iterable<Object> i = () -> java.util.Collection.emptyList().iterator();