### Question:
AkkaStreamsDemo implements ReactiveStreamsDemo { public void saveTextFileUsingGraph(List<String> text) { Sink.fromGraph(createFileSinkGraph()) .runWith(Source.from(text), materializer); }  static List<Integer> doSquares(); static List<Integer> doParallelSquares(); static CompletionStage<ArrayList<Integer>> parallelSquares(); static Materializer createMaterializer(); @Override java.util.concurrent.Future<List<Integer>> doSquaresAsync(int count); @Override java.util.concurrent.Future<String> doStringConcatAsync(int count); @Override java.util.concurrent.Future<List<Integer>> doParallelSquaresAsync(int count); @Override java.util.concurrent.Future<String> doParallelStringConcatAsync(int count); void printErrors(); Source<String, NotUsed> getMessages(); void setChannel(Channel channel); Sink<String, CompletionStage<IOResult>> lineSink(String filename); void saveTextFile(List<String> text); Graph<SinkShape<String>, NotUsed> createFileSinkGraph(); void saveTextFileUsingGraph(List<String> text); final Collection<String> messageList; }### Answer:
@Test public void testGraph() { demo.saveTextFileUsingGraph(Arrays.asList("foo", "bar")); }