Activiti 5.18 流程Model 转成 流程BPMN文件

        byte[] bpmnBytes = null;
        String filename = null;
        JsonNode editorNode = new ObjectMapper().readTree(repositoryService.getModelEditorSource(modelId));
        BpmnJsonConverter jsonConverter = new BpmnJsonConverter();
        BpmnModel model = jsonConverter.convertToBpmnModel(editorNode);
        filename = model.getMainProcess().getId() + ".bpmn20.xml";
        bpmnBytes = new BpmnXMLConverter().convertToXML(model);
        
        ByteArrayInputStream in = new ByteArrayInputStream(bpmnBytes);