Grafana cloudspout-button-panel plugin is not appending the Grafana dashboard variable value properly on the button-pannel url request?

Environment:

• CentOS 7
• Grafana 7.3.1

1. Adding the dashboard variable to HTTPS base URL in cloudspout-button-panel plugin REST Integration:

2. While sending the request to the back end server it's appending the dashboard variable name not the value:

NOTE: While providing the complete URL without Grafana dashboard variable it's work fine

How to use dashboard variable in the button plugin Rest Integration?

Edit:1 Dashboard variable is declared under dashboard-setting -> variables as below