title: Spring: request-payload with only one element
body: <p>I want implement a web-service which consumes only one named parameter in request-payload. In curl view it should be smth like:
  curl -X PATCH myurl.net/my_service -d "{mySingleParameter: 49}" </p>
  
  <p>I'm trying to do it with Spring, but I wondered that to map such payload to my method I must to declare a new class. Like:</p>
  
  <pre><code>...
  public static class PayloadWithSingleParamMSP{
    public Long mySingleParameter;
  }
  
  @RequestMapping(value = "my_service", method = RequestMethod.PATCH)
  public String myService(@RequestBody PayloadWithSingleParamMSP payload){
    Long valueWhichIReallyNeed = payload.mySingleParameter;
    //do job
    ...
  }
  ...
  </code></pre>
  
  <p>But is there a way to take value which I really need (mySingleParameter) directly?</p>