Ensure that cached-refdb compiles against 'stable-3.5'

Bug: Issue 16365
Change-Id: Ia5f815305fd102e13ad97efeceb7c173c12eef3c
diff --git a/src/main/java/com/googlesource/gerrit/plugins/cachedrefdb/CachedRefRepository.java b/src/main/java/com/googlesource/gerrit/plugins/cachedrefdb/CachedRefRepository.java
index 91e9bb6..ebe4146 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/cachedrefdb/CachedRefRepository.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/cachedrefdb/CachedRefRepository.java
@@ -172,7 +172,7 @@
   }
 
   @Override
-  public Set<ObjectId> getAdditionalHaves() {
+  public Set<ObjectId> getAdditionalHaves() throws IOException {
     return delegate.getAdditionalHaves();
   }
 
@@ -195,7 +195,7 @@
   }
 
   @Override
-  public Map<AnyObjectId, Set<Ref>> getAllRefsByPeeledObjectId() {
+  public Map<AnyObjectId, Set<Ref>> getAllRefsByPeeledObjectId() throws IOException {
     return delegate.getAllRefsByPeeledObjectId();
   }