Add cayenne-java-modules example.
diff --git a/cayenne-java-modules b/cayenne-java-modules
new file mode 160000
index 0000000..7358025
--- /dev/null
+++ b/cayenne-java-modules
@@ -0,0 +1 @@
+Subproject commit 73580252f0ad9ea5602cdd2ad22ea244e73f143c