Resolution: Won't Fix
Affects Version/s: Jena 3.0.0
Fix Version/s: None
There are two different constants for the default graph for what seemed at the time, slightly different situations. The idea was that quads from the default graph of a dataset would be Quad.defaultGraphIRI and quads created by parsers, would be Quad.defaultGraphNodeGenerated. The idea was that the output of the parser was "default graph" but it was being redirected into a named graph. This does not now seem useful.
Quad.defaultGraphIRI = <urn:x-arq:DefaultGraph>
Quad.defaultGraphNodeGenerated = <urn:x-arq:DefaultGraphNode>
In SPARQL, the application is using GRAPH <urn:x-arq:DefaultGraph>. Using <urn:x-arq:DefaultGraphNode> wil not work consistently.
The proposal is to combine these two as Quad.defaultGraphIRI, possible migrate to Quad.defaultGraph, or even a class or enum for the graph naming constants.
These constants should never have been written to disk in database, certainly not <urn:x-arq:DefaultGraphNode>, but just to make sure, the operation Quad.isDefaultGraph(Node) can take the old name into account for a release cycle.
Nearly all the changes are in tests where the expected output has been explicitly written into test results.
There is another, little used, constant – Quad.tripleInQuad – for when a triple is in a quad just to be transported around, meaning "meaningless", "unknown" or "doesn't matter". This would not change. It exists to be different from Quad.defaultGraphIRI.