samples: add subscription with filter example (#978)

* samples: add subscription with filter example

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* populate filter string

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

README.md

@@ -245,6 +245,7 @@ Samples are in the [`samples/`](https://github.com/googleapis/java-pubsub/tree/m
 | Create Pull Subscription Example | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreatePullSubscriptionExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreatePullSubscriptionExample.java) |
 | Create Push Subscription Example | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreatePushSubscriptionExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreatePushSubscriptionExample.java) |
 | Create Subscription With Dead Letter Policy Example | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreateSubscriptionWithDeadLetterPolicyExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreateSubscriptionWithDeadLetterPolicyExample.java) |
+| Create Subscription With Filtering | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreateSubscriptionWithFiltering.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreateSubscriptionWithFiltering.java) |
 | Create Subscription With Ordering | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreateSubscriptionWithOrdering.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreateSubscriptionWithOrdering.java) |
 | Create Topic Example | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreateTopicExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreateTopicExample.java) |
 | Create Topic With Schema Example | [source code](https://github.com/googleapis/java-pubsub/blob/main/samples/snippets/src/main/java/pubsub/CreateTopicWithSchemaExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-pubsub&page=editor&open_in_editor=samples/snippets/src/main/java/pubsub/CreateTopicWithSchemaExample.java) |

samples/snippets/src/main/java/pubsub/CreateSubscriptionWithFiltering.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package pubsub;
+
+// [START pubsub_create_subscription_with_filter]
+import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.ProjectTopicName;
+import com.google.pubsub.v1.Subscription;
+import java.io.IOException;
+
+public class CreateSubscriptionWithFiltering {
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "your-project-id";
+    String topicId = "your-topic-id";
+    String subscriptionId = "your-subscription-id";
+    String filter = "attributes.author=\"unknown\"";
+
+    createSubscriptionWithFilteringExample(projectId, topicId, subscriptionId, filter);
+  }
+
+  public static void createSubscriptionWithFilteringExample(
+      String projectId, String topicId, String subscriptionId, String filter) throws IOException {
+    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
+
+      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
+      ProjectSubscriptionName subscriptionName =
+          ProjectSubscriptionName.of(projectId, subscriptionId);
+
+      Subscription subscription =
+          subscriptionAdminClient.createSubscription(
+              Subscription.newBuilder()
+                  .setName(subscriptionName.toString())
+                  .setTopic(topicName.toString())
+                  // Receive messages with attribute key "author" and value "unknown".
+                  .setFilter(filter)
+                  .build());
+
+      System.out.println(
+          "Created a subscription with filtering enabled: " + subscription.getAllFields());
+    }
+  }
+}
+// [END pubsub_create_subscription_with_filter]

samples/snippets/src/test/java/pubsub/AdminIT.java

@@ -44,6 +44,7 @@ public class AdminIT {
   private static final String pullSubscriptionId = "iam-pull-subscription-" + _suffix;
   private static final String pushSubscriptionId = "iam-push-subscription-" + _suffix;
   private static final String orderedSubscriptionId = "iam-ordered-subscription-" + _suffix;
+  private static final String filteredSubscriptionId = "iam-filtered-subscription-" + _suffix;
   private static final String pushEndpoint = "https://my-test-project.appspot.com/push";
 
   private static final TopicName topicName = TopicName.of(projectId, topicId);
@@ -53,6 +54,8 @@ public class AdminIT {
       SubscriptionName.of(projectId, pushSubscriptionId);
   private static final SubscriptionName orderedSubscriptionName =
       SubscriptionName.of(projectId, orderedSubscriptionId);
+  private static final SubscriptionName filteredSubscriptionName =
+      SubscriptionName.of(projectId, filteredSubscriptionId);
 
   private static void requireEnvVar(String varName) {
     assertNotNull(
@@ -82,6 +85,7 @@ public void tearDown() throws Exception {
         subscriptionAdminClient.deleteSubscription(pullSubscriptionName);
         subscriptionAdminClient.deleteSubscription(pushSubscriptionName);
         subscriptionAdminClient.deleteSubscription(orderedSubscriptionName);
+        subscriptionAdminClient.deleteSubscription(filteredSubscriptionName);
       } catch (NotFoundException ignored) {
         // ignore this as resources may not have been created
       }
@@ -183,6 +187,14 @@ public void testAdmin() throws Exception {
     assertThat(bout.toString()).contains("Created a subscription with ordering");
     assertThat(bout.toString()).contains("enable_message_ordering=true");
 
+    bout.reset();
+    // Test create a subscription with filtering enabled
+    CreateSubscriptionWithFiltering.createSubscriptionWithFilteringExample(
+        projectId, topicId, filteredSubscriptionId, "attributes.author=\"unknown\"");
+    assertThat(bout.toString()).contains("Created a subscription with filtering enabled");
+    assertThat(bout.toString())
+        .contains("google.pubsub.v1.Subscription.filter=attributes.author=\"unknown\"");
+
     bout.reset();
     // Test delete subscription. Run twice to delete both pull and push subscriptions.
     DeleteSubscriptionExample.deleteSubscriptionExample(projectId, pullSubscriptionId);

samples/snippets/src/test/java/pubsub/SubscriberIT.java

@@ -21,8 +21,6 @@
 
 import com.google.api.core.ApiFuture;
 import com.google.api.core.ApiFutures;
-import com.google.api.gax.core.ExecutorProvider;
-import com.google.api.gax.core.InstantiatingExecutorProvider;
 import com.google.cloud.pubsub.v1.Publisher;
 import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
 import com.google.cloud.pubsub.v1.TopicAdminClient;
@@ -58,8 +56,6 @@ public class SubscriberIT {
   private static final TopicName topicName = TopicName.of(projectId, topicId);
   private static final ProjectSubscriptionName subscriptionName =
       ProjectSubscriptionName.of(projectId, subscriptionId);
-  private static final ExecutorProvider executorProvider =
-      InstantiatingExecutorProvider.newBuilder().setExecutorThreadCount(4).build();
 
   private static void requireEnvVar(String varName) {
     assertNotNull(