[dotnet] mark UseSpecCompliantProtocol obsolete and throw error when false (#10448)

Author: titusfortner

dotnet/src/webdriver/Chromium/ChromiumOptions.cs

@@ -190,10 +190,20 @@ public ChromiumAndroidOptions AndroidOptions
         /// should use the legacy OSS protocol dialect or a dialect compliant with the W3C
         /// WebDriver Specification.
         /// </summary>
+        [Obsolete("Spec Compliant Protocol is the only supported protocol")]
         public bool UseSpecCompliantProtocol
         {
             get { return this.useSpecCompliantProtocol; }
-            set { this.useSpecCompliantProtocol = value; }
+            set
+            {
+                if (!value)
+                {
+                    throw new ArgumentException("Only the spec compliant protocol is supported, " +
+                                                "Please update to W3C Syntax: " +
+                                                "https://www.selenium.dev/blog/2022/legacy-protocol-support/");
+                }
+                this.useSpecCompliantProtocol = true;
+            }
         }
 
         /// <summary>

dotnet/test/chrome/ChromeSpecificTests.cs

@@ -1,9 +1,26 @@
-using NUnit.Framework;
+using System;
+using NUnit.Framework;
+using OpenQA.Selenium.Environment;
 
 namespace OpenQA.Selenium.Chrome
 {
     [TestFixture]
     public class ChromeSpecificTests : DriverTestFixture
     {
+        [OneTimeTearDown]
+        public void RunAfterAnyTests()
+        {
+            EnvironmentManager.Instance.CloseCurrentDriver();
+            EnvironmentManager.Instance.WebServer.Stop();
+        }
+
+        [Test]
+        public void W3CFalse()
+        {
+            Assert.Throws<ArgumentException>(() => new ChromeOptions
+            {
+                UseSpecCompliantProtocol = false
+            });
+        }
     }
 }