docs(sample): normalize firestore sample's region tags (#453)

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

@@ -20,8 +20,10 @@
 import com.google.auth.oauth2.GoogleCredentials;
 import com.google.cloud.firestore.DocumentReference;
 // [START fs_include_dependencies]
+// [START firestore_setup_dependencies]
 import com.google.cloud.firestore.Firestore;
 import com.google.cloud.firestore.FirestoreOptions;
+// [END firestore_setup_dependencies]
 // [END fs_include_dependencies]
 import com.google.cloud.firestore.QueryDocumentSnapshot;
 import com.google.cloud.firestore.QuerySnapshot;
@@ -44,19 +46,23 @@ public class Quickstart {
    */
   public Quickstart() {
     // [START fs_initialize]
+    // [START firestore_setup_client_create]
     Firestore db = FirestoreOptions.getDefaultInstance().getService();
+    // [END firestore_setup_client_create]
     // [END fs_initialize]
     this.db = db;
   }
 
   public Quickstart(String projectId) throws Exception {
     // [START fs_initialize_project_id]
+    // [START firestore_setup_client_create_with_project_id]
     FirestoreOptions firestoreOptions =
         FirestoreOptions.getDefaultInstance().toBuilder()
             .setProjectId(projectId)
             .setCredentials(GoogleCredentials.getApplicationDefault())
             .build();
     Firestore db = firestoreOptions.getService();
+    // [END firestore_setup_client_create_with_project_id]
     // [END fs_initialize_project_id]
     this.db = db;
   }
@@ -74,6 +80,7 @@ void addDocument(String docName) throws Exception {
     switch (docName) {
       case "alovelace": {
         // [START fs_add_data_1]
+        // [START firestore_setup_dataset_pt1]
         DocumentReference docRef = db.collection("users").document("alovelace");
         // Add document data  with id "alovelace" using a hashmap
         Map<String, Object> data = new HashMap<>();
@@ -85,11 +92,13 @@ void addDocument(String docName) throws Exception {
         // ...
         // result.get() blocks on response
         System.out.println("Update time : " + result.get().getUpdateTime());
+        // [END firestore_setup_dataset_pt1]
         // [END fs_add_data_1]
         break;
       }
       case "aturing": {
         // [START fs_add_data_2]
+        // [START firestore_setup_dataset_pt2]
         DocumentReference docRef = db.collection("users").document("aturing");
         // Add document data with an additional field ("middle")
         Map<String, Object> data = new HashMap<>();
@@ -100,6 +109,7 @@ void addDocument(String docName) throws Exception {
 
         ApiFuture<WriteResult> result = docRef.set(data);
         System.out.println("Update time : " + result.get().getUpdateTime());
+        // [END firestore_setup_dataset_pt2]
         // [END fs_add_data_2]
         break;
       }

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

@@ -54,6 +54,7 @@ Map<String, Object> listenToDocument() throws Exception {
     final SettableApiFuture<Map<String, Object>> future = SettableApiFuture.create();
 
     // [START listen_to_document]
+    // [START firestore_listen_document]
     DocumentReference docRef = db.collection("cities").document("SF");
     docRef.addSnapshotListener(new EventListener<DocumentSnapshot>() {
       @Override
@@ -76,6 +77,7 @@ public void onEvent(@Nullable DocumentSnapshot snapshot,
         // [END_EXCLUDE]
       }
     });
+    // [END firestore_listen_document]
     // [END listen_to_document]
 
     return future.get(TIMEOUT_SECONDS, TimeUnit.SECONDS);
@@ -88,6 +90,7 @@ List<String> listenForMultiple() throws Exception {
     final SettableApiFuture<List<String>> future = SettableApiFuture.create();
 
     // [START listen_to_multiple]
+    // [START firestore_listen_query_snapshots]
     db.collection("cities")
         .whereEqualTo("state", "CA")
         .addSnapshotListener(new EventListener<QuerySnapshot>() {
@@ -113,6 +116,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
             // [END_EXCLUDE]
           }
         });
+    // [END firestore_listen_query_snapshots]
     // [END listen_to_multiple]
 
     return future.get(TIMEOUT_SECONDS, TimeUnit.SECONDS);
@@ -125,6 +129,7 @@ List<DocumentChange> listenForChanges() throws Exception {
     SettableApiFuture<List<DocumentChange>> future = SettableApiFuture.create();
 
     // [START listen_for_changes]
+    // [START firestore_listen_query_changes]
     db.collection("cities")
         .whereEqualTo("state", "CA")
         .addSnapshotListener(new EventListener<QuerySnapshot>() {
@@ -158,6 +163,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
             // [END_EXCLUDE]
           }
         });
+    // [END firestore_listen_query_changes]
     // [END listen_for_changes]
 
     return future.get(TIMEOUT_SECONDS, TimeUnit.SECONDS);
@@ -168,6 +174,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
    */
   void detachListener() {
     // [START detach_errors]
+    // [START firestore_listen_detach]
     Query query = db.collection("cities");
     ListenerRegistration registration = query.addSnapshotListener(
         new EventListener<QuerySnapshot>() {
@@ -184,6 +191,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
 
     // Stop listening to changes
     registration.remove();
+    // [END firestore_listen_detach]
     // [END detach_errors]
   }
 
@@ -192,6 +200,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
    */
   void listenErrors() {
     // [START listen_errors]
+    // [START firestore_listen_handle_error]
     db.collection("cities")
         .addSnapshotListener(new EventListener<QuerySnapshot>() {
           @Override
@@ -209,6 +218,7 @@ public void onEvent(@Nullable QuerySnapshot snapshots,
             }
           }
         });
+    // [END firestore_listen_handle_error]
     // [END listen_errors]
   }