Add default visibility to javatests/.

Bug: 203542767
Test: presubmit
Change-Id: I520a64c5758462d0329da305148e8c4a95782813
diff --git a/javatests/Android.bp b/javatests/Android.bp
new file mode 100644
index 0000000..1f93d12
--- /dev/null
+++ b/javatests/Android.bp
@@ -0,0 +1,18 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+    default_visibility: ["//packages/modules/SdkExtensions/javatests:__subpackages__"],
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}