--- a/src/goodjava/lucene/backup/BackupServer.java	Sun May 10 22:28:13 2020 -0600
+++ b/src/goodjava/lucene/backup/BackupServer.java	Sun May 10 22:48:15 2020 -0600
@@ -5,8 +5,8 @@
 import java.util.Map;
 import java.net.Socket;
 import java.net.ServerSocket;
-import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
 import javax.net.ssl.SSLServerSocketFactory;
 import javax.net.ssl.SSLServerSocket;
 import goodjava.util.SoftCacheMap;
@@ -39,7 +39,7 @@
 	}
 
 	private final File backupDir;
-	private static final ThreadPoolExecutor threadPool = (ThreadPoolExecutor)Executors.newCachedThreadPool();
+	private static final ExecutorService threadPool = Executors.newCachedThreadPool();
 	private static final Map<String,Backup> backups = new SoftCacheMap<String,Backup>();
 
 	public BackupServer(File backupDir) throws IOException {