code: public UserScenarioValidation createUserScenarioValidation(final int scenarioId) {
          return invoke(USER_SCENARIO_VALIDATIONS,
                  new RequestClosure<JsonObject>() {
                      @Override
                      public JsonObject call(Invocation.Builder request) {
                          JsonObject     json = Json.createObjectBuilder().add("user_scenario_id", scenarioId).build();
                          Entity<String> data = Entity.entity(json.toString(), MediaType.APPLICATION_JSON_TYPE);
                          return request.post(data, JsonObject.class);
                      }
                  },
                  new ResponseClosure<JsonObject, UserScenarioValidation>() {
                      @Override
                      public UserScenarioValidation call(JsonObject json) {
                          return new UserScenarioValidation(json);
                      }
                  }
          );
      }
docs: Creates (starts) a user scenario validation.
  
  @param scenarioId id of the scenario that should be validated
  @return {@link com.loadimpact.resource.UserScenarioValidation}