refactor(bigtable-snippets): shorten ByteString references and add missing imports

Author: jinseopkim0

java-bigtable/samples/snippets/src/main/java/com/example/bigtable/AuthorizedViewExample.java

@@ -174,12 +174,11 @@ public void createAuthorizedView() {
       try {
         AuthorizedView.SubsetView subsetView =
             AuthorizedView.SubsetView.newBuilder()
-                .addRowPrefixes(com.google.protobuf.ByteString.EMPTY)
+                .addRowPrefixes(ByteString.EMPTY)
                 .putFamilySubsets(
                     COLUMN_FAMILY,
                     AuthorizedView.FamilySubsets.newBuilder()
-                        .addQualifierPrefixes(
-                            com.google.protobuf.ByteString.copyFromUtf8(COLUMN_QUALIFIER_NAME))
+                        .addQualifierPrefixes(ByteString.copyFromUtf8(COLUMN_QUALIFIER_NAME))
                         .build())
                 .build();
         AuthorizedView authorizedViewObj =
@@ -208,11 +207,11 @@ public void updateAuthorizedView() {
       // Update to an authorized view permitting everything.
       AuthorizedView.SubsetView subsetView =
           AuthorizedView.SubsetView.newBuilder()
-              .addRowPrefixes(com.google.protobuf.ByteString.EMPTY)
+              .addRowPrefixes(ByteString.EMPTY)
               .putFamilySubsets(
                   COLUMN_FAMILY,
                   AuthorizedView.FamilySubsets.newBuilder()
-                      .addQualifierPrefixes(com.google.protobuf.ByteString.EMPTY)
+                      .addQualifierPrefixes(ByteString.EMPTY)
                       .build())
               .build();
       AuthorizedView authorizedViewObj =

java-bigtable/samples/snippets/src/main/java/com/example/bigtable/deletes/DropRowRangeExample.java

@@ -19,6 +19,7 @@
 // [START bigtable_drop_row_range]
 import com.google.bigtable.admin.v2.DropRowRangeRequest;
 import com.google.cloud.bigtable.admin.v2.BigtableTableAdminClientV2;
+import com.google.protobuf.ByteString;
 import java.io.IOException;
 
 public class DropRowRangeExample {
@@ -27,7 +28,7 @@ public void dropRowRange(String projectId, String instanceId, String tableId) th
       DropRowRangeRequest request =
           DropRowRangeRequest.newBuilder()
               .setName("projects/" + projectId + "/instances/" + instanceId + "/tables/" + tableId)
-              .setRowKeyPrefix(com.google.protobuf.ByteString.copyFromUtf8("phone#4c410523"))
+              .setRowKeyPrefix(ByteString.copyFromUtf8("phone#4c410523"))
               .build();
       tableAdminClient.dropRowRange(request);
     }

java-bigtable/samples/snippets/src/test/java/com/example/bigtable/AuthorizedViewExampleTest.java

@@ -36,6 +36,7 @@
 import com.google.cloud.bigtable.data.v2.models.AuthorizedViewId;
 import com.google.cloud.bigtable.data.v2.models.Row;
 import com.google.cloud.bigtable.data.v2.models.RowCell;
+import com.google.protobuf.ByteString;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -108,11 +109,11 @@ public void setup() throws Exception {
 
     AuthorizedView.SubsetView subsetView =
         AuthorizedView.SubsetView.newBuilder()
-            .addRowPrefixes(com.google.protobuf.ByteString.EMPTY)
+            .addRowPrefixes(ByteString.EMPTY)
             .putFamilySubsets(
                 COLUMN_FAMILY,
                 AuthorizedView.FamilySubsets.newBuilder()
-                    .addQualifierPrefixes(com.google.protobuf.ByteString.EMPTY)
+                    .addQualifierPrefixes(ByteString.EMPTY)
                     .build())
             .build();
     AuthorizedView authorizedViewObj =

java-bigtable/samples/snippets/src/test/java/com/example/bigtable/TableAdminExampleTest.java

@@ -20,6 +20,7 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import com.google.api.gax.rpc.NotFoundException;
 import com.google.bigtable.admin.v2.ColumnFamily;
 import com.google.bigtable.admin.v2.CreateTableRequest;
 import com.google.bigtable.admin.v2.GetTableRequest;