JavaScript callback support in httpClient is not working

Hi,

I'm trying httpClient in JavaScript policy to make mock target call with below snippet

function onComplete(response, error) {
  print("inside onComplete",response);
  print("error",error);
  if (response) {
    context.setVariable('example.status', response.status);
  } else {
    context.setVariable('example.error', 'Woops: ' + error);
  }
}

print("before hitting mock server");

// Function callback allowed as an argument. 
httpClient.get("http://mocktarget.apigee.net/json",onComplete);

Callback is not happening with above snippet, Can you please help on this?

If i make a call using waitForComplete() then i was able to see the response. The snippet used in this case is below

var ex1 = httpClient.get("http://mocktarget.apigee.net/json");
ex1.waitForComplete();
if (ex1.isSuccess()) {
  response1 = ex1.getResponse();
  print("response after waitForComplete",response1.content);
  context.setVariable('example.status',response1.status);
} else {
  error = ex1.getError();
  context.setVariable('example.error','Woops: ' + error);
}