code: private void visit(XmlSchemaChoice xsdChoice,
              RootCompositeType compositeTypes, String choiceTypeName) {
          Map < String, Object > alternatives = new LinkedHashMap < String, Object >();
          int fieldIndex = 0;
          for (XmlSchemaChoiceMember alternative : xsdChoice.getItems()) {
              if (alternative instanceof XmlSchemaElement) {
                  addField(fieldIndex, alternative, alternatives, compositeTypes);
                  fieldIndex++;
              }
          }
          compositeTypes.choiceTypes.put(choiceTypeName, alternatives);
  
      }
docs: Visit each alternative of a choice in turn.
  <p/>
  Note that this produces a new complex type.
  
  @param xsdChoice the XML schema choice
  @param compositeTypes the lists of composite types being populated
  @param choiceTypeName the name to use for this choice type