chore: fix viewConfig in AutomatedBackupPolicy (#2604)

Author: mutianf

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/admin/v2/models/Table.java

@@ -18,6 +18,7 @@
 
 import com.google.api.core.InternalApi;
 import com.google.bigtable.admin.v2.TableName;
+import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
@@ -128,8 +129,10 @@ public com.google.bigtable.admin.v2.Table.AutomatedBackupPolicy toProto() {
 
     /** Returns policy config contents as a string. */
     public String viewConfig() {
-      AutomatedBackupPolicy config = fromProto(proto);
-      return config.proto.getAllFields().toString();
+      return MoreObjects.toStringHelper(this)
+          .add(proto.getClass().getName() + ".retention_period", proto.getRetentionPeriod())
+          .add(proto.getClass().getName() + ".frequency", proto.getFrequency())
+          .toString();
     }
   }
 

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/admin/v2/models/TableTest.java

@@ -90,11 +90,11 @@ public void testFromProto() {
     assertThat(result.isAutomatedBackupEnabled()).isTrue();
     assertEquals(
         result.getAutomatedBackupPolicy().viewConfig(),
-        "{google.bigtable.admin.v2.Table.AutomatedBackupPolicy.retention_period=seconds: 1\n"
+        "AutomatedBackupPolicy{com.google.bigtable.admin.v2.Table$AutomatedBackupPolicy.retention_period=seconds: 1\n"
             + //
             "nanos: 99\n"
             + //
-            ", google.bigtable.admin.v2.Table.AutomatedBackupPolicy.frequency=seconds: 1\n"
+            ", com.google.bigtable.admin.v2.Table$AutomatedBackupPolicy.frequency=seconds: 1\n"
             + //
             "nanos: 99\n"
             + //