Hide use of private WorkQueue.Executor for Gerrit master

Change-Id: I7be2ebaa575f2102e0a6f5caf650124c6e06f39e

src/main/java/com/googlesource/gerrit/plugins/download/command/project/DownloadCommandUpdater.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/download/command/project/DownloadCommandUpdater.java b/src/main/java/com/googlesource/gerrit/plugins/download/command/project/DownloadCommandUpdater.java
index ce0f857..7fc1631 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/download/command/project/DownloadCommandUpdater.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/download/command/project/DownloadCommandUpdater.java
@@ -28,7 +28,6 @@
 import com.google.gerrit.server.git.MetaDataUpdate;
 import com.google.gerrit.server.git.ProjectConfig;
 import com.google.gerrit.server.git.WorkQueue;
-import com.google.gerrit.server.git.WorkQueue.Executor;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.inject.Inject;
@@ -41,6 +40,7 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.Map;
 
 @Singleton
@@ -55,7 +55,7 @@
   private final ProjectCache projectCache;
   private final Map<String, ProjectDownloadCommand> projectDownloadCommands;
   private final Map<String, RegistrationHandle> registrationHandles;
-  private final Executor executor;
+  private final ScheduledExecutorService executor;
 
   @Inject
   DownloadCommandUpdater(@PluginName String pluginName,