On a further look I can see that Relation::backwards returns null because "http://www.w3.org/2001/XMLSchema#"; is not in the cols map. https://github.com/apache/jena/blob/main/jena-core/src/main/java/org/apache/jena/rdfxml/xmloutput/impl/Relation.java#L204
That's where my investigation ends, I'm afraid... On Wed, Jul 13, 2022 at 5:51 PM Martynas Jusevičius <marty...@atomgraph.com> wrote: > > I can see that this.getPrefixFor( value ) returns null, where value is > "http://www.w3.org/2001/XMLSchema#";. > https://github.com/apache/jena/blob/main/jena-core/src/main/java/org/apache/jena/rdfxml/xmloutput/impl/BaseXMLWriter.java#L229 > > No idea why though. > > On Wed, Jul 13, 2022 at 5:03 PM Martynas Jusevičius > <marty...@atomgraph.com> wrote: > > > > Hi, > > > > Never seen this exception before and not sure yet what causes it: > > > > java.lang.NullPointerException: Cannot invoke "String.equals(Object)" > > because "prefix" is null > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.checkLegalPrefix(BaseXMLWriter.java:845) > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.setNsPrefix(BaseXMLWriter.java:324) > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.primeNamespace(BaseXMLWriter.java:232) > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.setupNamespaces(BaseXMLWriter.java:482) > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.write(BaseXMLWriter.java:466) > > org.apache.jena.rdfxml.xmloutput.impl.BaseXMLWriter.write(BaseXMLWriter.java:456) > > com.atomgraph.linkeddatahub.server.io.ValidatingModelProvider.write(ValidatingModelProvider.java:129) > > > > Any hints?
