spring annotation method argument performance issue test

AppTests.java

@Before
public void setup() throws Exception {
    this.mockMvc = webAppContextSetup(this.wac).build();

    // warm up
    for (int i = 0; i < 3000; i++) {
        this.mockMvc.perform(post("/")
                .contentType(MediaType.APPLICATION_JSON)
                .header("Dooray-App-Key", UUID.randomUUID().toString()))
                .andExpect(status().isOk())
                .andReturn();
    }
}

@Test
public void simple() throws Exception {
    StopWatch watch = new StopWatch();

    watch.start();
    for (int i = 0; i < 50000; i++) {
        if (i%5000 == 0) {
            watch.stop();
            System.out.println(watch.getTotalTimeMillis());
            watch.start();
        }
        this.mockMvc.perform(post("/")
                .contentType(MediaType.APPLICATION_JSON)
                .header("Dooray-App-Key", UUID.randomUUID().toString()))
                .andExpect(status().isOk())
                .andReturn();
    }
    watch.stop();
    System.out.println(watch.getTotalTimeMillis());
}

HelloController.java

@RestController
@RequestMapping("/")
public class HelloController {
    @ModelAttribute("DoorayAppKey")
    public String getDoorayAppKey(@RequestHeader("Dooray-App-Key") String doorayAppKey) {
        return doorayAppKey;
    }

    @RequestMapping(method = RequestMethod.POST)
    public String printAppKey(@ModelAttribute("DoorayAppKey") String doorayAppKey) {
        return "{ \"doorayAppKey\": \"" + doorayAppKey + "\" }";
    }
}