title: concatenate two value from the yaml file in the global configuration in mule 4
body: <p>I have to set the property placeholder dynamically from the runtime. I'm configuring ${mule.env} in the runtime but when i'm trying to append this in into the placeholder i'm getting error that value not found and error in the ${mule.env}_${secure::sfdc.token.host}.
  How can I append the ${mule.env} into the ${secure::sfdc.token.host} so that it will take correct configuration value.
  Below i have added my request-config and YAML.</p>
  
  <pre><code>    &lt;http:request-config name="HTTP_Request_configuration-token" doc:name="HTTP Request configuration" doc:id="411c1d32-df92-44da-87d9-cca02e851db7" basePath="${mule.env}_${secure::sfdc.token.base_path}"&gt;
      &lt;http:request-connection host="${mule.env}_${secure::sfdc.token.host}" /&gt;
      &lt;/http:request-config&gt; 
  </code></pre>
  
  <p>yaml:</p>
  
  <pre><code>       uat_sfdc:
           token:
              base_path: "/services/uat"
              host: "0.0.0.0"
         prod_sfdc:
           token:
              base_path: "/services/prod"
              host: "0.0.0.0"
  </code></pre>