TurtleDocumentFormat: can't parse `PREFIX`

PREFIX is a modern alternative for @prefix: https://www.w3.org/TR/turtle/#turtle-prefixes

following testcase fails with exception:

        String ttl = """
                PREFIX dc:   <http://purl.org/dc/elements/1.1/>
                PREFIX owl:  <http://www.w3.org/2002/07/owl#>
                PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
                PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
                PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>
                """;
        OWLOntology owl = OntManagers.createOWLAPIImplManager().loadOntologyFromOntologyDocument(
                new StringDocumentSource(ttl, IRI.create("x"), new TurtleDocumentFormat(), "ttl")
        );
        owl.saveOntology(System.out);

Exception in thread "main" org.semanticweb.owlapi.io.UnparsableOntologyException: Problem parsing x
Could not parse ontology.  Either a suitable parser could not be found, or parsing failed.  See parser logs below for explanation.
The following parsers were tried:
1) org.semanticweb.owlapi.rdf.turtle.parser.TurtleOntologyParser@724f138e

Detailed logs:
--------------------------------------------------------------------------------
Parser: org.semanticweb.owlapi.rdf.turtle.parser.TurtleOntologyParser@724f138e
    Stack trace:
org.semanticweb.owlapi.rdf.turtle.parser.ParseException: Encountered unexpected token: "PREFIX" <PN_LOCAL>
    at line 1, column 1.

Was expecting one of:

    "("
    "@base"
    "@prefix"
    "["
    <EMPTY_BLANK_NODE>
    <FULLIRI>
    <NODEID>
    <PNAME_LN>
    <PNAME_NS>
        org.semanticweb.owlapi.rdf.turtle.parser.TurtleOntologyParser.parse(TurtleOntologyParser.java:58)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyFactoryImpl.loadOWLOntology(OWLOntologyFactoryImpl.java:195)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.load(OWLOntologyManagerImpl.java:1105)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntology(OWLOntologyManagerImpl.java:1055)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:1005)
        com.github.owlcs.ontapi.tmp.TmpTurtleInvestigation.main(TmpTurtleInvestigation.java:25)
Encountered unexpected token: "PREFIX" <PN_LOCAL>
    at line 1, column 1.

Was expecting one of:

    "("
    "@base"
    "@prefix"
    "["
    <EMPTY_BLANK_NODE>
    <FULLIRI>
    <NODEID>
    <PNAME_LN>
    <PNAME_NS>
        org.semanticweb.owlapi.rdf.turtle.parser.TurtleParser.generateParseException(TurtleParser.java:1034)
        org.semanticweb.owlapi.rdf.turtle.parser.TurtleParser.jj_consume_token(TurtleParser.java:902)
        org.semanticweb.owlapi.rdf.turtle.parser.TurtleParser.parseDocument(TurtleParser.java:165)
        org.semanticweb.owlapi.rdf.turtle.parser.TurtleOntologyParser.parse(TurtleOntologyParser.java:54)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyFactoryImpl.loadOWLOntology(OWLOntologyFactoryImpl.java:195)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.load(OWLOntologyManagerImpl.java:1105)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntology(OWLOntologyManagerImpl.java:1055)
        uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:1005)
        com.github.owlcs.ontapi.tmp.TmpTurtleInvestigation.main(TmpTurtleInvestigation.java:25)

    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyFactoryImpl.loadOWLOntology(OWLOntologyFactoryImpl.java:236)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.load(OWLOntologyManagerImpl.java:1105)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntology(OWLOntologyManagerImpl.java:1055)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:1005)

owlcs / owlapi

TurtleDocumentFormat: can't parse `PREFIX` #1149