chore: Fix compile issues

Author: lqiu96

google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1/it/ITBigQueryStorageWriteClientTest.java

@@ -56,7 +56,9 @@
 import com.google.protobuf.DescriptorProtos.FieldDescriptorProto;
 import com.google.protobuf.Descriptors;
 import com.google.protobuf.Descriptors.DescriptorValidationException;
+import com.google.protobuf.DynamicMessage;
 import com.google.protobuf.Int64Value;
+import com.google.protobuf.Message;
 import io.grpc.Status;
 import io.grpc.Status.Code;
 import java.io.ByteArrayOutputStream;