WebEngine.getDocument().getDocumentURI() no longer returns null for loading a String of HTML

In Java 8 U121 and earlier, if you called WebView.loadContent on an Html String and called javafx.scene.web.WebEngine.getDocument().getDocumentUri() the answer was always null, now the answer is "about:blank". Previously this result was reserved for pages were loaded with "about:blank" directly.

Attached is a reproducible test case that shows the change in behavior between Java 8 U121 and Java 8 U131 which broke our application.

Is this something you can put back?
Is this a documented change?
If you can't put it back, how do we now tell the difference between a page that was loaded with "about:blank" and an html string that was passed into the WebEngine.loadContent("Html String")?

We have customers using webstart who will have their JREs automatically upgraded to Java 8 U 131 and our application will break because of this change.