Class Loader

I have two jar files that contains two 'RispostaDocument' classes. The first one 'it.visura.assi.xmlbeans.navigazione.imprese.risposta.RispostaDocument'
is the class that i want to use. There is another class 'it.visura.assi.xmlbeans.navigazione.assettiproprietari.risposta.soci.impl.RispostaDocument' that is the class that is actually used.

When the findDocumentTypeRef(QName ) is called the class founded in the 'documentCache' is a ''it.visura.assi.xmlbeans.navigazione.assettiproprietari.risposta.soci.impl.RispostaDocument' ' while i had instantiate the first one

'it.visura.assi.xmlbeans.navigazione.imprese.risposta-RispostaDocument rispostaDocument = 'it.visura.assi.xmlbeans.navigazione.imprese.risposta.RispostaDocument.Factory.parse(messaggio2)";

public SchemaType.Ref findDocumentTypeRef(QName name)
{
Object cached = _documentCache.get(name);
if (cached == CACHED_NOT_FOUND)
return null;
SchemaType.Ref result = (SchemaType.Ref) cached;
if (result == null)
{
for (int i = 0; i < _searchPath.length; i++)
if (null != (result = _searchPath[i].findDocumentTypeRef(name)))
break;
if (result == null)
{
SchemaTypeSystem ts = typeSystemForComponent("schema" + METADATA_PACKAGE_LOAD + "/element/", name);
if (ts != null)

{ result = ts.findDocumentTypeRef(name); assert(result != null) : "Type system registered element " + QNameHelper.pretty(name) + " but does not contain document type"; }

}
_documentCache.put(name, result == null ? CACHED_NOT_FOUND : result);
}
return result;
}