How property can be owl:DatatypeProperty and owl:ObjectProperty at the same time.

property classification bug

@prefix :        <http://example.com/test/> .
@prefix test:  <http://example.com/test/> .
@prefix owl:     <http://www.w3.org/2002/07/owl#> .
@prefix qudt:    <http://qudt.org/schema/qudt#> .
@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#> .

<http://example.com/test/>
      rdf:type owl:Ontology .

test:Agent
    rdf:type owl:Class ;
    rdfs:subClassOf
      [ rdf:type owl:Restriction ;
        owl:minCardinality "1"^^xsd:nonNegativeInteger ;
        owl:onProperty test:id
      ] .

      
test:id
    rdf:type owl:DatatypeProperty ;
    rdfs:domain test:Agent ;
    rdfs:range xsd:string .     
    
test:string1024
  rdf:type rdfs:Datatype ;
  rdfs:label "string1024"^^xsd:string ;
  rdfs:subClassOf xsd:string ;
  owl:equivalentClass
		  [ rdf:type rdfs:Datatype ;
			owl:onDatatype xsd:string ;
			owl:withRestrictions
					([ xsd:maxLength "1024"^^xsd:nonNegativeInteger
					  ])
		  ] .