feat: hidi validate command now logs warnings

src/Microsoft.OpenApi.Hidi/OpenApiService.cs

@@ -398,6 +398,7 @@ private static async Task<ReadResult> ParseOpenApiAsync(string openApiFile, bool
                 logger.LogTrace("{Timestamp}ms: Completed parsing.", stopwatch.ElapsedMilliseconds);
 
                 LogErrors(logger, result);
+                LogWarnings(logger, result);
                 stopwatch.Stop();
             }
 
@@ -652,7 +653,7 @@ private static string GetInputPathExtension(string? openapi = null, string? csdl
         private static void LogErrors(ILogger logger, ReadResult result)
         {
             var context = result.Diagnostic;
-            if (context is not null && context.Errors.Count != 0)
+            if (context is { Errors.Count: > 0 })
             {
                 using (logger.BeginScope("Detected errors"))
                 {
@@ -664,6 +665,21 @@ private static void LogErrors(ILogger logger, ReadResult result)
             }
         }
 
+        private static void LogWarnings(ILogger logger, ReadResult result)
+        {
+            var context = result.Diagnostic;
+            if (context is { Warnings.Count: > 0 })
+            {
+                using (logger.BeginScope("Detected warnings"))
+                {
+                    foreach (var warning in context.Warnings)
+                    {
+                        logger.LogWarning("Detected warning during parsing: {Warning}", warning.ToString());
+                    }
+                }
+            }
+        }
+
         internal static void WriteTreeDocumentAsMarkdown(string openapiUrl, OpenApiDocument document, StreamWriter writer)
         {
             var rootNode = OpenApiUrlTreeNode.Create(document, "main");