[src] Fix a few nullablity issues in a few places.

src/CoreImage/CIFilter.cs

@@ -136,7 +136,7 @@ internal CIFilter (string name)
 		///         <summary>Returns an array of strings that specifies the filters taht the system provides for the specified <paramref name="categories" />.</summary>
 		///         <returns>To be added.</returns>
 		///         <remarks>To be added.</remarks>
-		public static string [] FilterNamesInCategories (params string [] categories)
+		public static string [] FilterNamesInCategories (params string []? categories)
 		{
 			return _FilterNamesInCategories (categories);
 		}

src/Security/Policy.cs

@@ -46,13 +46,11 @@ internal SecPolicy (NativeHandle handle, bool owns)
 		[DllImport (Constants.SecurityLibrary)]
 		extern static IntPtr /* SecPolicyRef */ SecPolicyCreateSSL (byte server, IntPtr /* CFStringRef */ hostname);
 
+		/// <summary>Create a policy instance that represents the SSL/TLS profile.</summary>
 		/// <param name="server">Indicate if the policy is for a server (true) or client (false) certificate.</param>
-		///         <param name="hostName">The server host name on which the policy will be applied.</param>
-		///         <summary>Create a policy instance that represent the SSL/TLS profile.</summary>
-		///         <returns>A SecPolicy instance that can be used to validate a SecCertificate using SecTrust.</returns>
-		///         <remarks>
-		///         </remarks>
-		static public SecPolicy CreateSslPolicy (bool server, string hostName)
+		/// <param name="hostName">The server host name on which the policy will be applied, or <see langword="null" /> to create a policy without a specific host name (disables host name validation).</param>
+		/// <returns>A SecPolicy instance that can be used to validate a SecCertificate using SecTrust.</returns>
+		static public SecPolicy CreateSslPolicy (bool server, string? hostName)
 		{
 			var handle = CFString.CreateNative (hostName);
 			try {

src/SystemConfiguration/NetworkReachability.cs

@@ -370,13 +370,15 @@ public NetworkReachability (string address)
 		[ObsoletedOSPlatform ("maccatalyst17.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
 		[ObsoletedOSPlatform ("tvos17.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
 		[ObsoletedOSPlatform ("macos14.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
-		static IntPtr Create (IPAddress localAddress, IPAddress remoteAddress)
+		static IntPtr Create (IPAddress? localAddress, IPAddress? remoteAddress)
 		{
 			if (localAddress is null && remoteAddress is null)
 				throw new ArgumentException ("At least one address is required");
 
 			IntPtr handle;
 			if (localAddress is null) {
+				if (remoteAddress is null)
+					throw new ArgumentException ("At least one address is required");
 				var remote = new sockaddr_in (remoteAddress);
 
 				unsafe {
@@ -411,7 +413,7 @@ static IntPtr Create (IPAddress localAddress, IPAddress remoteAddress)
 		[ObsoletedOSPlatform ("maccatalyst17.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
 		[ObsoletedOSPlatform ("tvos17.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
 		[ObsoletedOSPlatform ("macos14.4", "Use 'NSUrlSession' or 'NWConnection' instead.")]
-		public NetworkReachability (IPAddress localAddress, IPAddress remoteAddress)
+		public NetworkReachability (IPAddress? localAddress, IPAddress? remoteAddress)
 			: base (Create (localAddress, remoteAddress), true)
 		{
 		}

tests/introspection/ApiCoreImageFiltersTest.cs

@@ -88,7 +88,7 @@ public void CheckNativeFilters ()
 			int n = 0;
 			string qname = CIFilterType.AssemblyQualifiedName;
 			// that will give us only the list of filters supported by the executing version of iOS
-			foreach (var filter_name in CIFilter.FilterNamesInCategories (null)) {
+			foreach (var filter_name in CIFilter.FilterNamesInCategories ()) {
 				if (Skip (filter_name))
 					continue;
 				string type_name = qname.Replace ("CIFilter", filter_name);
@@ -108,7 +108,7 @@ public void CheckManagedFilters ()
 		{
 			Errors = 0;
 			ContinueOnFailure = true;
-			List<string> filters = new List<string> (CIFilter.FilterNamesInCategories (null));
+			var filters = new List<string> (CIFilter.FilterNamesInCategories ());
 			var superFilters = new List<string> ();
 			var nspace = CIFilterType.Namespace;
 			var types = CIFilterType.Assembly.GetTypes ();

tests/monotouch-test/CoreImage/FilterTest.cs

@@ -127,5 +127,16 @@ public void CIVectorArray ()
 				Assert.Null (f.Mesh, "Mesh/Null/again");
 			}
 		}
+
+		[Test]
+		public void FilterNamesInCategories ()
+		{
+			var a = CIFilter.FilterNamesInCategories ();
+			var b = CIFilter.FilterNamesInCategories (null);
+
+			Assert.That (a, Is.EquivalentTo (b), "Filtering");
+			Assert.That (a.Length, Is.GreaterThan (0), "Filtered A");
+			Assert.That (b.Length, Is.GreaterThan (0), "Filtered B");
+		}
 	}
 }