Don't inject empty tree artifact

src/main/java/com/google/devtools/build/lib/remote/RemoteActionFileSystem.java

@@ -154,7 +154,12 @@ void flush() throws IOException {
                 }
               });
 
-          metadataInjector.injectTree(parent, tree.build());
+          var metadata = tree.build();
+          // Don't inject empty tree metadata, in case that tree files are generated locally,
+          // skyframe has the change to read metadata from local filesystem.
+          if (!metadata.getChildren().isEmpty()) {
+            metadataInjector.injectTree(parent, metadata);
+          }
         }
       } else {
         RemoteFileInfo remoteFile =

src/test/shell/bazel/remote/build_without_the_bytes_test.sh

@@ -1341,4 +1341,46 @@ EOF
   expect_log "bin-message"
 }
 
+function test_tree_artifact_from_local_file_system() {
+  # Test that tree artifact generated locally can be consumed by other actions.
+  # See https://github.com/bazelbuild/bazel/issues/16789
+
+  mkdir -p a
+  cat > a/my_rule.bzl <<'EOF'
+def _impl(ctx):
+  out = ctx.actions.declare_directory(ctx.label.name)
+  ctx.actions.run_shell(
+    outputs = [out],
+    command = "echo '1' > {out}/my_file".format(out = out.path),
+  )
+  return DefaultInfo(
+    files = depset([out]),
+    runfiles = ctx.runfiles(files = [out])
+  )
+my_rule = rule(
+  implementation = _impl,
+  attrs = {},
+)
+EOF
+  cat > a/out_dir_test.sh <<'EOF'
+cat $1/my_file
+EOF
+  chmod a+x a/out_dir_test.sh
+  cat > a/BUILD <<'EOF'
+load(":my_rule.bzl", "my_rule")
+my_rule(name = "out_dir")
+sh_test(
+  name = "out_dir_test",
+  srcs = ["out_dir_test.sh"],
+  args = ["$(rootpath :out_dir)"],
+  data = [":out_dir"],
+)
+EOF
+
+  bazel test \
+    --remote_cache=grpc://localhost:${worker_port} \
+    --remote_download_minimal \
+    //a:out_dir_test >& $TEST_log || fail "Failed to test //a:out_dir_test"
+}
+
 run_suite "Build without the Bytes tests"