fix: correct validation rules for v2

Author: bielu

src/ByteBard.AsyncAPI.Readers/AsyncApiJsonDocumentReader.cs

@@ -139,6 +139,7 @@ public T ReadFragment<T>(JsonNode input, AsyncApiVersion version, out AsyncApiDi
             where T : IAsyncApiElement
         {
             diagnostic = new AsyncApiDiagnostic();
+            diagnostic.SpecificationVersion = version;
             this.context ??= new ParsingContext(diagnostic, this.settings)
             {
                 ExtensionParsers = this.settings.ExtensionParsers,
@@ -363,7 +364,10 @@ private IAsyncApiSerializable ResolveStreamReference(Stream stream, IAsyncApiRef
                 }
             }
 
-            AsyncApiDiagnostic fragmentDiagnostic = new AsyncApiDiagnostic();
+            AsyncApiDiagnostic fragmentDiagnostic = new AsyncApiDiagnostic
+            {
+                SpecificationVersion = diagnostic.SpecificationVersion,
+            };
             IAsyncApiSerializable result = null;
             switch (reference.Reference.Type)
             {

src/ByteBard.AsyncAPI/Validation/Rules/AsyncApiServerRules.cs

@@ -6,6 +6,7 @@
     [AsyncApiRule]
     public static class AsyncApiServerRules
     {
+        [AsyncApiVersionRule(AsyncApiVersion.AsyncApi3_0)]
         public static ValidationRule<AsyncApiServer> ServerRequiredFields =>
             new ValidationRule<AsyncApiServer>(
                 (context, server) =>
@@ -28,6 +29,32 @@ public static class AsyncApiServerRules
                             string.Format(Resource.Validation_FieldRequired, "protocol", "server"));
                     }
 
+                    context.Exit();
+                });
+
+        [AsyncApiVersionRule(AsyncApiVersion.AsyncApi2_0)]
+        public static ValidationRule<AsyncApiServer> V2ServerRequiredFields =>
+            new ValidationRule<AsyncApiServer>(
+                (context, server) =>
+                {
+                    context.Enter("url");
+                    if (server.Host == null)
+                    {
+                        context.CreateError(
+                            nameof(V2ServerRequiredFields),
+                            string.Format(Resource.Validation_FieldRequired, "url", "server"));
+                    }
+ 
+                    context.Exit();
+
+                    context.Enter("protocol");
+                    if (server.Protocol == null)
+                    {
+                        context.CreateError(
+                            nameof(V2ServerRequiredFields),
+                            string.Format(Resource.Validation_FieldRequired, "protocol", "server"));
+                    }
+
                     context.Exit();
                 });
     }