wso2esb - How to access service parameter from WSO2 ESB sequence -

I have configured proxy service parameters according to the document:

    
 Now I need to access it from within the sequence, is there any way to do this?  
 I tried to use this script intermediary:  
  & lt; Script language = "js" & gt; Mc.setProperty ("TestParamProp", Mc.getParameter ("TestParam") & lt; / Script & gt;   
 But it throws "Can not get the function getParameter." Error.  
 Please advise. Use the following to access the ESB parameter   
 
 
 Script intermediary  
 < Code> & lt; Script language = "js" & gt; Var test_param = mc.getProperty ('TestParam') & lt; / Script & gt;   
 Use the script to return the parameter back to the ESB within the mediator  
  mc.setProperty ("newParam", test_param)