Handling of source documents
Support for JDOM version 1 is dropped. Applications should switch to JDOM2.
Support for Saxon PTree files is dropped. PTree was a binary serialization format for XML documents. It never achieved the (space or time) performance characteristics of alternative third-party solutions such as EXI, which can be readily used for the same purpose.
There have been significant internal changes to the implementation of XSLT 3.0 streaming; this should have no effect on applications, except to make a few cases streamable that were not previously handled. The basic architecture, whereby evaluation of child expressions triggers evaluation of parent expressions by passing events up a push pipeline, remains unchanged, but the actual implementation of the pipeline has changed considerably; in particular it is now closely aligned with the push pipeline interfaces used by the schema validator and the serializer, which enables much better re-use of code.