code: public GetInstanceVncResponse getInstanceVnc(GetInstanceVncRequest request) {
          checkNotNull(request, "request should not be null.");
          checkStringNotEmpty(request.getInstanceId(), "request instanceId should not be empty.");
          InternalRequest internalRequest = this.createRequest(
                  request, HttpMethodName.GET, INSTANCE_PREFIX, request.getInstanceId(), "vnc");
          return this.invokeHttpClient(internalRequest, GetInstanceVncResponse.class);
      }
docs: Getting the vnc url to access the instance.
  
  The vnc url can be used once.
  
  @param request The request containing all options for getting the vnc url.