Using XJC to generate code from a DTD is less capable then generating code from an XSD, see these links for similar historically unresolved issues:

• jaxb-multiple-content-for-element
• DTD to JAXB2 compilation problem

If you can convert your DTD to XSD ...

Description.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
    <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>
    <xs:element name="Description">
        <xs:complexType mixed="true">
            <xs:sequence>
                <xs:element minOccurs="0" maxOccurs="unbounded" ref="ShortName"/>
            </xs:sequence>
            <xs:attribute ref="xml:lang" use="required"/>
        </xs:complexType>
    </xs:element>
    <xs:element name="ShortName" type="xs:string"/>
</xs:schema>

... then XJC can generate code like this ...

Description.java

// This file was generated by the Eclipse Implementation of JAXB, v4.0.5 
// and modified to reduce space.
package generated;

import java.io.Serializable;
import java.util.*;
import jakarta.xml.bind.JAXBElement;
import jakarta.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = { "content" })
@XmlRootElement(name = "Description")
public class Description
{
    @XmlElementRef(name = "ShortName", type = JAXBElement.class, required = false)
    @XmlMixed
    protected List<Serializable> content;
    public List<Serializable> getContent()
    {
        if (content == null)
            content = new ArrayList<>();
        return this.content;
    }

    @XmlAttribute(name = "lang", namespace = "http://www.w3.org/XML/1998/namespace", required = true)
    protected String lang;
    public String getLang()
    {
        return lang;
    }
    public void setLang(String value)
    {
        this.lang = value;
    }
}