Define unstable container

Unstable container marks modules that are static reverse dependencies of
"framework-minus-apex". These modules contain unstable implementation
details of the platform, and should not be accessed by the CTS tests.

Test: m nothing
Bug: 338660802
Change-Id: Ia0e1b3070f0f7b2c1b9c27306323e2428d9722ca
diff --git a/java/testing.go b/java/testing.go
index e1bf537..0e85022 100644
--- a/java/testing.go
+++ b/java/testing.go
@@ -542,6 +542,16 @@
 			},
 			compile_dex: true,
 		}
+		java_library {
+			name: "framework-minus-apex",
+			srcs: ["a.java"],
+			sdk_version: "none",
+			system_modules: "stable-core-platform-api-stubs-system-modules",
+			aidl: {
+				export_include_dirs: ["framework/aidl"],
+			},
+			compile_dex: true,
+		}
 
 		android_app {
 			name: "framework-res",