Update to use RefNames constants

Gerrit change I76e6ee7e63a4549b51a43698fb50b54a19dabfc6

Change-Id: I1d1383d1c8964add688b7626e4a86df88e7965e4

src/main/java/com/googlesource/gerrit/plugins/download/command/RepoCommand.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/download/command/RepoCommand.java b/src/main/java/com/googlesource/gerrit/plugins/download/command/RepoCommand.java
index 7f11bed..5a1eafb 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/download/command/RepoCommand.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/download/command/RepoCommand.java
@@ -16,6 +16,7 @@
 
 import com.google.gerrit.extensions.config.DownloadCommand;
 import com.google.gerrit.extensions.config.DownloadScheme;
+import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.server.config.DownloadConfig;
 import com.google.inject.Inject;
 
@@ -39,7 +40,7 @@
   }
 
   private static String trim(String ref) {
-    if (ref.startsWith("refs/changes/")) {
+    if (ref.startsWith(RefNames.REFS_CHANGES)) {
       int s1 = ref.lastIndexOf('/');
       if (s1 > 0) {
         int s2 = ref.lastIndexOf('/', s1 - 1);