Reification is only supported in the Model API, not Graph. It's already
simpler than it was when first introduced, when it had 3 different modes.
The complexity on storage was huge.
https://www.hpl.hp.com/techreports/2003/HPL-2003-266.pdf
Reification subsequently got simplified to library code in the Model API
which corresponds to the original "Reification standard mode".
https://jena.apache.org/documentation/notes/reification_previous.html
See ReifierStd, which is all static functions. (There are no
"hiddenTriples" - that was an old feature)
Andy
