Minor grammar update (PR feedback).

        /// <summary>

        /// Tests the failure case of trying to add a sponsored user

        /// when the maximum number are already on the console.

        /// when the maximum number is already on the console.

        /// </summary>

        [TestMethod]

        public void AddSponsoredUserTest_Failure()

        {

            HttpResponseMessage response = new HttpResponseMessage((HttpStatusCode)422);

            HttpContent content = new StringContent(

                "{\"ErrorCode\":-2136866553,\"ErrorMessage\":\"The maximum number of sponsored users are already signed in.\"}", 

                "{\"ErrorCode\":-2136866553,\"ErrorMessage\":\"The maximum number of sponsored users is already signed in.\"}", 

                System.Text.Encoding.UTF8, 

                "application/json");

                DevicePortalException exception = e.InnerException as DevicePortalException;

                Assert.AreEqual(-2136866553, exception.HResult);

                Assert.AreEqual("The maximum number of sponsored users are already signed in.", exception.Reason);

                Assert.AreEqual("The maximum number of sponsored users is already signed in.", exception.Reason);

            }

        }

    }