[BUG] - The IRIs for the OML backbone constructs may clash with the vocabulary IRIs

Description

A clear and concise description of what the bug is.

Steps to Reproduce

Steps to reproduce the behavior:

[ ] Consider this vocabulary:

vocabulary <http://example.org/iris> with # as iris {

    concept Aspect
    concept Concept
    concept ReifiedRelationship
    concept StructuredDatatype

}

The vocabulary IRIs clash with the backbone IRIs for OML constructs as shown below:

<?xml version="1.0"?>
<rdf:RDF xmlns="http://example.org/iris#"
     xml:base="http://example.org/iris"
     xmlns:oml="http://opencaesar.io/oml#"
     xmlns:owl="http://www.w3.org/2002/07/owl#"
     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:xml="http://www.w3.org/XML/1998/namespace"
     xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
     xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">
    <owl:Ontology rdf:about="http://example.org/iris">
        <owl:imports rdf:resource="http://opencaesar.io/oml#"/>
        <oml:ontologyType>http://opencaesar.io/oml#Vocabulary</oml:ontologyType>
    </owl:Ontology>

    <!-- 
    ///////////////////////////////////////////////////////////////////////////////////////
    //
    // Annotation properties
    //
    ///////////////////////////////////////////////////////////////////////////////////////
     -->

    <!-- http://opencaesar.io/oml#ontologyType -->

    <owl:AnnotationProperty rdf:about="http://opencaesar.io/oml#ontologyType"/>

    <!-- 
    ///////////////////////////////////////////////////////////////////////////////////////
    //
    // Classes
    //
    ///////////////////////////////////////////////////////////////////////////////////////
     -->

    <!-- http://example.org/iris#Aspect -->

    <owl:Class rdf:about="http://example.org/iris#Aspect">
        <rdfs:subClassOf rdf:resource="http://opencaesar.io/oml#Concept"/>
    </owl:Class>

    <!-- http://example.org/iris#Concept -->

    <owl:Class rdf:about="http://example.org/iris#Concept">
        <rdfs:subClassOf rdf:resource="http://opencaesar.io/oml#Concept"/>
    </owl:Class>

    <!-- http://example.org/iris#ReifiedRelationship -->

    <owl:Class rdf:about="http://example.org/iris#ReifiedRelationship">
        <rdfs:subClassOf rdf:resource="http://opencaesar.io/oml#Concept"/>
    </owl:Class>

    <!-- http://example.org/iris#StructuredDatatype -->

    <owl:Class rdf:about="http://example.org/iris#StructuredDatatype">
        <rdfs:subClassOf rdf:resource="http://opencaesar.io/oml#Concept"/>
    </owl:Class>

    <!-- http://opencaesar.io/oml#Concept -->

    <owl:Class rdf:about="http://opencaesar.io/oml#Concept"/>
</rdf:RDF>

<!-- Generated by the OWL API (version 5.1.12.2019-10-20T12:26:29Z) https://github.com/owlcs/owlapi/ -->

Expected Behavior

A clear and concise description of what should be the expected behavior.

All OML backbone entities should have IRIs that, by convention, are clearly differentiated from the vocabulary IRIs; e.g., by prefixing http://opencaesar.io/backbone/ to the vocabulary IRI.

For example, if the vocabulary IRI is http://example.org/iris, the backbone IRI would be http://opencaesar.io/backbone/example.org/iris

Additional Context

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opencaesar / owl-adapter