Jena complains about wrong prefixes in tests

in many tests we see the following log:

2022-12-29 00:27:32.183 DEBUG 26372 --- [main] e.g.d.f.c.s.v.i.VerificationServiceImpl : verifySelfDescription; content parsed, time taken: 1 2022-12-29 00:27:32.183 DEBUG 26372 --- [main] e.g.d.f.c.s.v.i.VerificationServiceImpl : verifyPresentation.enter; got presentation with id: presentationID 2022-12-29 00:27:32.183 DEBUG 26372 --- [main] e.g.d.f.c.s.v.i.VerificationServiceImpl : initLoaders; Setting up Caching com.apicatalog.jsonld DocumentLoader 2022-12-29 00:27:32.183 DEBUG 26372 --- [main] e.g.d.f.c.s.v.i.VerificationServiceImpl : getStreamManager; Setting up Jena caching Locator 2022-12-29 00:27:32.192 WARN 26372 --- [main] org.apache.jena.riot.lang.LangJSONLD11 : Unexpected problem while extracting prefixes: null

java.lang.NullPointerException: null at org.apache.jena.riot.lang.LangJSONLD11.extractPrefixes(LangJSONLD11.java:107) at org.apache.jena.riot.lang.LangJSONLD11.extractPrefixes(LangJSONLD11.java:99) at org.apache.jena.riot.lang.LangJSONLD11.read(LangJSONLD11.java:76) at org.apache.jena.riot.lang.LangJSONLD11.read(LangJSONLD11.java:67) at org.apache.jena.riot.RDFParser.read(RDFParser.java:370) at org.apache.jena.riot.RDFParser.parseNotUri(RDFParser.java:356) at org.apache.jena.riot.RDFParser.parse(RDFParser.java:306) at org.apache.jena.riot.RDFParser.parse(RDFParser.java:252) at org.apache.jena.riot.RDFParser.parse(RDFParser.java:261) at org.apache.jena.riot.RDFParserBuilder.parse(RDFParserBuilder.java:576) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl$TypedCredentials.getSDType(VerificationServiceImpl.java:844) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl$TypedCredentials.getSDTypes(VerificationServiceImpl.java:821) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl$TypedCredentials.initCredentials(VerificationServiceImpl.java:718) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl$TypedCredentials.(VerificationServiceImpl.java:704) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl.getCredentials(VerificationServiceImpl.java:336) at eu.gaiax.difs.fc.core.service.verification.impl.VerificationServiceImpl.verifyPresentation(VerificationServiceImpl.java:283)

something is wrong with our test JSONLD files?