Do not expose cache-automerge refs

Change-Id: I0dc28f7f73034b0198da304284b12a0469f63cb2
diff --git a/src/main/java/com/googlesource/gerrit/modules/gitrefsfilter/ForProjectWrapper.java b/src/main/java/com/googlesource/gerrit/modules/gitrefsfilter/ForProjectWrapper.java
index 2860870..b477670 100644
--- a/src/main/java/com/googlesource/gerrit/modules/gitrefsfilter/ForProjectWrapper.java
+++ b/src/main/java/com/googlesource/gerrit/modules/gitrefsfilter/ForProjectWrapper.java
@@ -80,6 +80,7 @@
         .filter(refs, repo, opts)
         .parallelStream()
         .filter((ref) -> !ref.getName().startsWith(RefNames.REFS_USERS))
+        .filter((ref) -> !ref.getName().startsWith(RefNames.REFS_CACHE_AUTOMERGE))
         .filter(
             (ref) -> {
               String refName = ref.getName();