获取nvisual-Token
This collection will not be listed publicly until it contains something.
 
            To add a node or flow, use the add button in the thing's drop-down menu, or select the 'add to collection' option on the item's page.
每条需要调用nVisual接口的流程都需要事先该节点。用于收集用户的用户名和密码以及api的连接地址,保证token的有效性以支撑整条流程的正常运行