make sure the src-dir is checked in
diff --git a/experimental/swt/org.eclipse.fx.sample.singlesource.app/src/donotdelete b/experimental/swt/org.eclipse.fx.sample.singlesource.app/src/donotdelete
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/experimental/swt/org.eclipse.fx.sample.singlesource.app/src/donotdelete