Improvements in SSL accept handler

- Replace sslProtocols collection with parameter.
- Replace call to AuthenticateAsServer to remove requirement for client certificate.
- Lock object is now initialized in constructor.
- Correct typos in comments.
- Bump version to 1.2.2-preview.

Signed-off-by: José Simões <jose.simoes@eclo.solutions>

source/nanoFramework.System.Net.Http/Http/System.Net.HttpListener.cs

@@ -22,7 +22,7 @@ namespace System.Net
     /// </remarks>
     public class HttpListener
     {
-        private readonly object lockObj = new object();
+        private readonly object lockObj;
 
         /// <summary>
         /// Indicates whether the listener is waiting on an http or https
@@ -122,6 +122,8 @@ public SslProtocols SslProtocols
         /// class has no arguments.</remarks>
         public HttpListener(string prefix)
         {
+            lockObj = new object();
+
             InitListener(prefix, -1);
         }
 
@@ -137,6 +139,8 @@ public HttpListener(string prefix)
         /// class has no arguments.</remarks>
         public HttpListener(string prefix, int port)
         {
+            lockObj = new object();
+
             InitListener(prefix, port);
         }
 
@@ -405,11 +409,13 @@ private void AcceptThreadFunc()
                     else
                     {
                         // This is the case of https.
-                        // Once connection estiblished need to create secure stream and authenticate server.
+                        // Once connection established need to create secure stream and authenticate server.
                         netStream = new SslStream(clientSock);
 
-                        // Throws exception if fails.
-                        ((SslStream)netStream).AuthenticateAsServer(m_httpsCert, m_sslProtocols);
+                        // Throws exception if this fails
+                        // pass the server certificate
+                        // do not require client certificate
+                        ((SslStream)netStream).AuthenticateAsServer(m_httpsCert, false,  m_sslProtocols);
 
                         netStream.ReadTimeout = 10000;
                     }
@@ -591,7 +597,7 @@ public void Stop()
         /// </example>
         public HttpListenerContext GetContext()
         {
-            // Protects access for simulteneous call for GetContext and Close or Stop.
+            // Protects access for simultaneous call for GetContext and Close or Stop.
             lock (lockObj)
             {
                 if (m_Closed) throw new ObjectDisposedException();
@@ -666,8 +672,7 @@ public int MaximumResponseHeadersLength
 
 #pragma warning disable S2292 // Trivial properties should be auto-implemented
         /// <summary>
-        /// The certificate used if <b>HttpListener</b> implements an https
-        /// server.
+        /// The certificate used if <see cref="HttpListener"/> implements an https server.
         /// </summary>
         public X509Certificate HttpsCert
 #pragma warning restore S2292 // Trivial properties should be auto-implemented

source/version.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/AArnott/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
-  "version": "1.2.1-preview.{height}",
+  "version": "1.2.2-preview.{height}",
   "assemblyVersion": {
     "precision": "revision"
   },