Add filegroups used in api-stubs generation.

Bug: b/70351683
Test: m api-stubs-doc
Change-Id: I6902eefcead830e1c5fe89dc198dbdae75ba3e5d
diff --git a/JavaLibrary.bp b/JavaLibrary.bp
index d96b63e..813b6db 100644
--- a/JavaLibrary.bp
+++ b/JavaLibrary.bp
@@ -297,3 +297,10 @@
     todo_file: "core-docs-todo.html",
     args: "-offlinemode -title \"libcore\"",
 }
+
+filegroup {
+    name: "known-oj-tags",
+    srcs: [
+        "known_oj_tags.txt",
+    ],
+}