fix(readme): update readme snippets (#31)

Author: anguillanneuf

README.md

@@ -19,8 +19,9 @@
 
  ```java
  import com.google.cloud.pubsublite.kafka.ProducerSettings;
- import org.apache.kafka.clients.producer.*;
  import com.google.cloud.pubsublite.*;
+
+ import org.apache.kafka.clients.producer.*;
 
  ...
 
@@ -51,17 +52,22 @@
 1. Read some messages using:
 
  ```java
+ import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
  import com.google.cloud.pubsublite.kafka.ConsumerSettings;
- import org.apache.kafka.clients.consumer.*;
  import com.google.cloud.pubsublite.*;
-  import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
- 
+ 
+ import org.apache.kafka.clients.consumer.*;
  ...
 
  private final static String ZONE = "us-central1-b";
  private final static Long PROJECT_NUM = 123L;
 
  ...
+ TopicPath topic = TopicPath.newBuilder()
+ .setLocation(CloudZone.parse(ZONE))
+ .setProject(ProjectNumber.of(PROJECT_NUM))
+ .setName(TopicName.of("my-topic"))
+ .build();
 
  SubscriptionPath subscription = SubscriptionPath.newBuilder()
  .setLocation(CloudZone.parse(ZONE))
@@ -75,11 +81,13 @@
  .setBytesOutstanding(10_000_000) // 10 MB
  .setMessagesOutstanding(Long.MAX_VALUE)
  .build())
- .setAutocommit(true);
+ .setAutocommit(true)
+ .build();
 
  try (Consumer<byte[], byte[]> consumer = settings.instantiate()) {
+ consumer.subscribe(Arrays.asList(topic.toString()));
  while (true) {
- ConsumerRecords<byte[], byte[]> records = consumer.poll(Long.MAX_VALUE);
+ ConsumerRecords<byte[], byte[]> records = consumer.poll(Duration.ofSeconds(30));
  for (ConsumerRecord<byte[], byte[]> record : records) {
  System.out.println(record.offset() + “: ” + record.value());
  }