docs: add a snippet and test for a Firestore client with a regional

endpoint

samples/install-without-bom/pom.xml

@@ -34,6 +34,12 @@
     </dependency>
     <!-- [END firestore_install_without_bom] -->
 
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-firestore-admin</artifactId>
+      <version>3.9.3</version>
+    </dependency>
+
     <!--  used for beam samples-->
     <dependency>
       <groupId>org.apache.beam</groupId>

samples/snippets/pom.xml

@@ -48,6 +48,10 @@
     </dependency>
     <!-- [END firestore_install_with_bom] -->
 
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-firestore-admin</artifactId>
+    </dependency>
     <!--  used for beam samples-->
     <dependency>
       <groupId>org.apache.beam</groupId>

samples/snippets/src/main/java/com/example/firestore/snippets/RegionalEndpointSnippets.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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 com.example.firestore.snippets;
+
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.firestore.Firestore;
+import com.google.cloud.firestore.FirestoreOptions;
+
+
+/**
+ * Snippets to demonstrate how to set a regional endpoint.
+ */
+public class RegionalEndpointSnippets {
+
+  /**
+   * Create a client with a regional endpoint.
+   **/
+  public Firestore regionalEndpoint(String projectId, String endpoint) throws Exception {
+    // [START firestore_regional_endpoint]
+    FirestoreOptions firestoreOptions =
+        FirestoreOptions.newBuilder()
+            .setProjectId(projectId)
+            .setCredentials(GoogleCredentials.getApplicationDefault())
+            // set endpoint like nam5-firestore.googleapis.com:443
+            .setHost(endpoint)
+            .build();
+    Firestore dbWithEndpoint = firestoreOptions.getService();
+    // [END firestore_regional_endpoint]
+    return dbWithEndpoint;
+  }
+
+}

samples/snippets/src/test/java/com/example/firestore/snippets/RegionalEndpointSnippetsIT.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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 com.example.firestore.snippets;
+
+import static org.junit.Assert.assertNotNull;
+
+import com.example.firestore.BaseIntegrationTest;
+import com.google.api.core.ApiFuture;
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.firestore.DocumentReference;
+import com.google.cloud.firestore.DocumentSnapshot;
+import com.google.cloud.firestore.Firestore;
+import com.google.cloud.firestore.FirestoreOptions;
+import com.google.cloud.firestore.v1.FirestoreAdminClient;
+import com.google.firestore.admin.v1.Database;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+
+@RunWith(JUnit4.class)
+@SuppressWarnings("checkstyle:abbreviationaswordinname")
+public class RegionalEndpointSnippetsIT extends BaseIntegrationTest {
+
+  private static RegionalEndpointSnippets regionalEndpointSnippets;
+
+  private static FirestoreAdminClient adminClient;
+
+  private static String getEnvVar(String varName) {
+    String value = System.getenv(varName);
+    assertNotNull(
+        String.format("Environment variable '%s' must be set to perform these tests.", varName),
+        value);
+    return value;
+  }
+
+  @BeforeClass
+  public static void setUpBeforeClass() throws Exception {
+    regionalEndpointSnippets = new RegionalEndpointSnippets();
+
+    adminClient = FirestoreAdminClient.create();
+  }
+
+  @Test
+  public void testRegionalEndoint() throws Exception {
+    projectId = getEnvVar("FIRESTORE_PROJECT_ID");
+    // Get database location of the default database in the project
+    Database dbInfo = adminClient.getDatabase("projects/" + projectId + "/databases/(default)");
+    String locationId = dbInfo.getLocationId();
+
+    // Test regional endpoint with same location as default database
+    Firestore dbWithEndpoint = regionalEndpointSnippets.regionalEndpoint(projectId,
+        locationId + "-firestore.googleapis.com:443");
+    assertNotNull(dbWithEndpoint);
+
+    // Retrieve a document to confirm client connection
+    DocumentReference docRef = dbWithEndpoint.collection("cities").document("SF");
+    // asynchronously retrieve the document
+    ApiFuture<DocumentSnapshot> future = docRef.get();
+    assertNotNull(future);
+
+    dbWithEndpoint.close();
+  }
+
+  @AfterClass
+  public static void tearDownAfterClass() throws Exception {
+    db.close();
+    adminClient.close();
+  }
+}