Saxon

See http://stackoverflow.com/questions/43387074/accessing-unparsed-entities-in-xslt-with-a-saxtransformerfactory-and-transformer

Saxon's JAXP identity transformer drops unparsed entities. It appears that the JDK version doesn't.

This can be fixed by adding simple implementations of setUnparsedEntity() to two classes: the ComplexContentOutputter, and the ContentHandlerProxy. It needs a little care, however. In the SAX interface, unparsed entity events are set to a DTDHandler, and in general we might expect that a DTDHandler won't know what to do with unparsed entity events if the rest of the DTD isn't being passed as well. Also the DTDHandler interface expects the notation name to be preserved, while the notation name of an unparsed entity is not included in XDM and therefore cannot be passed down the Saxon Receiver pipeline.

Passing unparsed entities through the identity transformer probably isn't enough to achieve compatibility with the JDK version, because it's quite possible that the JDK version retains the whole DTD, plus other things like CDATA sections.

I think we have a clean story though if (a) the identity transformer retains everything that is retained in XDM, and (b) we only emit unparsed entities if we know the recipient is a TransformerHandler, not a general DTDHandler.