public void setFlowletInstances(String applicationId, String flowId, String flowletName, int instances) {
MockResponder responder = new MockResponder();
String uri = String.format("/v2/apps/%s/flows/%s/flowlets/%s/instances/%s",
applicationId, flowId, flowletName, instances);
HttpRequest request = new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.PUT, uri);
JsonObject json = new JsonObject();
json.addProperty("instances", instances);
request.setContent(ChannelBuffers.wrappedBuffer(json.toString().getBytes()));
httpHandler.setFlowletInstances(request, responder, applicationId, flowId, flowletName);
Preconditions.checkArgument(responder.getStatus().getCode() == 200, "set flowlet instances failed");
}