remote: add directory support for remote caching and execution

Add support for directory trees as artifacts. Closes #4011.

PiperOrigin-RevId: 179691001
diff --git a/src/test/java/com/google/devtools/build/lib/remote/RemoteSpawnCacheTest.java b/src/test/java/com/google/devtools/build/lib/remote/RemoteSpawnCacheTest.java
index 65c7d88..b14fb71 100644
--- a/src/test/java/com/google/devtools/build/lib/remote/RemoteSpawnCacheTest.java
+++ b/src/test/java/com/google/devtools/build/lib/remote/RemoteSpawnCacheTest.java
@@ -87,7 +87,7 @@
   private Path execRoot;
   private SimpleSpawn simpleSpawn;
   private FakeActionInputFileCache fakeFileCache;
-  @Mock private RemoteActionCache remoteCache;
+  @Mock private AbstractRemoteActionCache remoteCache;
   private RemoteSpawnCache cache;
   private FileOutErr outErr;