For network performance we choose to set externalize-feature-libs to true to lower ifr response sizes. On the other hand we also have some default-forced-libs.
We have discovered that in this case the external script tag inserted two times one for the default-forced-libs, other for the gadget features. With JS servlet being unaware of there are two separate requests, the transitive dependencies included twice, as a result of this, some of the core libraries included twice.
This behavior can be tested with setting externalize-feature-libs to true on default java server and running sample-pubsub-2.html from browser.
The correct implementation should combine the two library requests into one to avoid double-load.