The type com.sun.webkit.network.URLLoader.java is defined in two places (and that makes my IDE unhappy among other badness of having two copies of the same file).

On copy is in
javafx-ui-webnode/src/com/sun/webkit/network/URLLoader.java

and the other is in:
webkit/src/com/sun/webkit/network/URLLoader.java

They are almost exactly the same file, the only differences is that the first had the patch in RT-24709 applied to it

I believe you could delete anyone you like, but it seems the copy in 'javafx-ui-webnode' a bit out of place and the copy is 'webkit' is the one in the right place.

If it was me I would apply the patch in RT-24709 to the 'webkit' version and delete the copy in 'javafx-ui-webnode'.

I was able to build rt-closed regardless of each file I deleted.