fix: fix channel not shut down properly exception.

Client being created has to be properly closed, otherwise during garbage
collection an error will be reported showing channel not shutdown
properly

Author: GaoleMeng

samples/snippets/src/main/java/com/example/bigquerystorage/WriteToDefaultStream.java

@@ -49,7 +49,7 @@
 import org.threeten.bp.Duration;
 
 public class WriteToDefaultStream {
-
+  
   public static void runWriteToDefaultStream()
       throws DescriptorValidationException, InterruptedException, IOException {
     // TODO(developer): Replace these variables before running the sample.
@@ -138,6 +138,8 @@ private static class DataWriter {
 
     private static final int MAX_RECREATE_COUNT = 3;
 
+    private BigQueryWriteClient client;
+
     // Track the number of in-flight requests to wait for all responses before shutting down.
     private final Phaser inflightRequestCount = new Phaser(1);
     private final Object lock = new Object();
@@ -163,12 +165,16 @@ public void initialize(TableName parentTable)
               .setMaxRetryDelay(Duration.ofMinutes(1))
               .build();
 
+      // Initialize client without settings, internally within stream writer a new client will be
+      // created with full settings.
+      client = BigQueryWriteClient.create();
+
       // Use the JSON stream writer to send records in JSON format. Specify the table name to write
       // to the default stream.
       // For more information about JsonStreamWriter, see:
       // https://googleapis.dev/java/google-cloud-bigquerystorage/latest/com/google/cloud/bigquery/storage/v1/JsonStreamWriter.html
       streamWriter =
-          JsonStreamWriter.newBuilder(parentTable.toString(), BigQueryWriteClient.create())
+          JsonStreamWriter.newBuilder(parentTable.toString(), client)
               .setExecutorProvider(
                   FixedExecutorProvider.create(Executors.newScheduledThreadPool(100)))
               .setChannelProvider(
@@ -195,7 +201,7 @@ public void append(AppendContext appendContext)
             && recreateCount.getAndIncrement() < MAX_RECREATE_COUNT) {
           streamWriter =
               JsonStreamWriter.newBuilder(
-                      streamWriter.getStreamName(), BigQueryWriteClient.create())
+                      streamWriter.getStreamName(), client)
                   .build();
           this.error = null;
         }
@@ -217,6 +223,7 @@ public void cleanup() {
       // Wait for all in-flight requests to complete.
       inflightRequestCount.arriveAndAwaitAdvance();
 
+      client.close();
       // Close the connection to the server.
       streamWriter.close();