Activiti7.1.0.M6中，SequenceFlow标签可以通过扩展BPMNXMLConverter来新增自定义属性

是的，SequenceFlow标签可以通过扩展BPMNXMLConverter来新增自定义属性。

在 Activiti7.1.0.M6 版本中，SequenceFlow 标签可以通过扩展 BPMNXMLConverter 类来新增自定义属性。具体做法如下：

1. 创建一个类，继承自 org.activiti.bpmn.converter.BPMNXMLConverter 类。

2. 重写 convertToXML 方法，在该方法中添加自定义属性。

3. 在 Activiti7 的配置文件中配置自定义的 BPMNXMLConverter 类。

例如，我们可以创建一个 CustomBPMNXMLConverter 类来添加自定义属性，具体代码如下：

public class CustomBPMNXMLConverter extends BPMNXMLConverter {

    @Override
    protected void convertSequenceflow(XMLStreamReader xtr, BpmnModel model, Process activeProcess) throws Exception {
        super.convertSequenceflow(xtr, model, activeProcess);
        SequenceFlow sequenceFlow = (SequenceFlow) model.getFlowElement(findCurrentFlowElement(xtr));
        //添加自定义属性
        sequenceFlow.setCustomProperty("myCustomProperty", "customValue");
    }
    
}

然后，在 Activiti7 的配置文件中配置 CustomBPMNXMLConverter，具体配置如下：

<bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration">
    <property name="customPostBPMNParseListeners">
        <list>
            <bean class="org.activiti.engine.impl.bpmn.parser.factory.DefaultBpmnParseFactory">
                <property name="bpmnParser">
                    <bean class="org.activiti.bpmn.converter.BpmnXMLConverter">
                        <property name="converters">
                            <list>
                                <bean class="org.activiti.bpmn.converter.StartEventXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.EndEventXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.SequenceFlowXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ThrowEventXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.BusinessRuleTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.MailTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ManualTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ReceiveTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ScriptTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ServiceTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.UserTaskXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.CallActivityXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.SubProcessXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.EventGatewayXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ExclusiveGatewayXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.InclusiveGatewayXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.ParallelGatewayXMLConverter"/>
                                <bean class="org.activiti.bpmn.converter.TransactionXMLConverter"/>
                                <bean class="com.example.CustomBPMNXMLConverter"/> <!-- 添加自定义的 BPMNXMLConverter -->
                            </list>
                        </property>
                    </bean>
                </property>
            </bean>
        </list>
    </property>
</bean>

这样，我们就可以通过扩展 BPMNXMLConverter 类来新增自定义属性了。