The markup declarations contained or pointed to by the document type declaration must be well-formed

Hibernate ORM
16

Hello,
To answer with our current usecase:
with this URL it fails
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

with this one it works
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

OS: Windows 11, Google cloud, On Prem… (Not related to OS)
JDK: OpenJDK8, Amazon Corretto 11
SpringBoot, old application… (Not related)
Hibernate-Version: 3.1.3 (at least)
Sample of hmb.xml

 <?xml version='1.0' encoding='utf-8'?>
 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 
 <hibernate-mapping>
     <class name="NAME" table="table_name" schema="schema">
         <id name="Id" column="column_id">
            <generator class="native" />
        </id>
         <many-to-one name="child" class="Child" column="child_id" not-null="true" fetch="join" lazy="false"/>
       
         <property name="property1" column="column_property1"/>
         <property name="property1" column="column_property2"/>
       
    </class>
</hibernate-mapping>

Sample of error message:

2022-02-24 16:21:17.267 ERROR xxxxxx:61 - Error parsing XML: XML InputStream(1) The markup declarations contained or pointed to by the document type declaration must be well-formed.
2022-02-24 16:21:17.272 ERROR xxxxxxx:52 - server error org.hibernate.MappingException: Could not read mappings from resource:  xxxxxx.hbm.xml