Difficult to determine enumeration types from generated OWL/SHACL file

Context: to generate the Java code from the OWL/SHACL file, we need to determine if a particular class is an enumeration type

Based on the information available in the OWL/SHACL file, we would have to find all property references to the class and do some rather messy heuristics to determine if a particular class is an Enum class.

Suggestion is to add some information at the class level to more accurately and easily determine if a class represents an Enum with a limited range of values.

Currently, it looks like the only hints as to whether a class is an Enum class is in the properties whose range is that class.

Details:

The current generated file only has basic information for a class containing only enumerated values. For example, HashAlgorithm is defined only containing the comment:

ns2:HashAlgorithm a owl:Class ;
    rdfs:comment "A mathematical algorithm that maps data of arbitrary size to a bit string."@en .

The individuals defined for that class can be a hint, but they only have a label and a comment. Example:

<https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/adler32> a owl:NamedIndividual,
        ns2:HashAlgorithm ;
    rdfs:label "adler32" ;
    rdfs:comment "Adler-32 checksum is part of the widely used zlib compression library as defined in [RFC 1950](https://datatracker.ietf.org/doc/rfc1950/) Section 2.3."@en .

The properties which are limited to the class do provide a restriction which can be useful.

Example:

ns2:Hash a owl:Class,
        sh:NodeShape ;
    rdfs:comment "A mathematically calculated representation of a grouping of data."@en ;
    rdfs:subClassOf ns2:IntegrityMethod ;
    sh:nodeKind sh:BlankNode ;
    sh:property [ sh:datatype xsd:string ;
            sh:maxCount 1 ;
            sh:minCount 1 ;
            sh:nodeKind sh:Literal ;
            sh:path ns2:hashValue ],
        [ sh:class ns2:HashAlgorithm ;
            sh:in ( <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/adler32> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/blake2b256> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/blake2b384> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/blake2b512> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/blake3> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/crystalsDilithium> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/crystalsKyber> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/falcon> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/md2> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/md4> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/md5> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/md6> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/other> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha1> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha224> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha256> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha384> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha512> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha3_224> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha3_256> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha3_384> <https://spdx.org/rdf/3.0.1/terms/Core/HashAlgorithm/sha3_512> ) ;
            sh:maxCount 1 ;
            sh:minCount 1 ;
            sh:nodeKind sh:IRI ;
            sh:path ns2:algorithm ] .

Start by reviewing the spec-parser generation flow and the OWL/SHACL examples in the issue, especially the HashAlgorithm class and the Hash property restriction. Determine how a class-level enum marker should be represented and how generated Java code can consume it; done means enum classes can be identified without property-reference heuristics.