Source without statements loses all top-level comments during 'migrate'

[codeworrior]

While working on https://github.com/SAP/openui5/commit/c782ce9be8cbd71201e19ba3cb4c0e81e439b71f , I encountered the following issue with the ui5-migration tooling:

The file src/sap.m/src/sap/m/SelectionDetailsFacade.js which contains only JSDoc comments, was converted to sap.ui.define (not necessary) and all comments went lost.

After (this is the whole file)

sap.ui.define([], function() {
"use strict";
});

To reproduce, you can execute the following commands

cd openui5
git checkout 6555a38
ui5-migration migrate src/sap.m/src/sap/m/SelectionDetailsFacade.js