public static Read<String> readStrings() {
    return Read.newBuilder(
            (PubsubMessage message) -> new String(message.getPayload(), StandardCharsets.UTF_8))
        .setCoder(StringUtf8Coder.of())
        .build();
  }
@Test
  public void testNullSubscription() {
    String topic = "projects/project/topics/topic";
    PubsubIO.Read<String> read = PubsubIO.readStrings().fromTopic(StaticValueProvider.of(topic));
    assertNotNull(read.getTopicProvider());
    assertNull(read.getSubscriptionProvider());
    assertNotNull(DisplayData.from(read));
  }