Always emitting description property for response object. It's required

Author: VitaliyKurokhtin

src/Microsoft.OpenApi/Models/OpenApiResponse.cs

@@ -3,7 +3,6 @@
 
 using System.Collections.Generic;
 using System.Linq;
-using Microsoft.OpenApi.Any;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Writers;
 
@@ -45,7 +44,7 @@ public class OpenApiResponse : IOpenApiSerializable, IOpenApiReferenceable, IOpe
         /// <summary>
         /// Indicates if object is populated with data or is just a reference to the data
         /// </summary>
-        public bool UnresolvedReference { get; set;}
+        public bool UnresolvedReference { get; set; }
 
         /// <summary>
         /// Reference pointer.
@@ -79,7 +78,7 @@ public void SerializeAsV3WithoutReference(IOpenApiWriter writer)
             writer.WriteStartObject();
 
             // description
-            writer.WriteProperty(OpenApiConstants.Description, Description);
+            writer.WriteRequiredProperty(OpenApiConstants.Description, Description);
 
             // headers
             writer.WriteOptionalMap(OpenApiConstants.Headers, Headers, (w, h) => h.SerializeAsV3(w));
@@ -123,7 +122,7 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
             writer.WriteStartObject();
 
             // description
-            writer.WriteProperty(OpenApiConstants.Description, Description);
+            writer.WriteRequiredProperty(OpenApiConstants.Description, Description);
             if (Content != null)
             {
                 var mediatype = Content.FirstOrDefault();

src/Microsoft.OpenApi/Writers/OpenApiWriterExtensions.cs

@@ -32,6 +32,19 @@ public static void WriteProperty(this IOpenApiWriter writer, string name, string
             writer.WriteValue(value);
         }
 
+        /// <summary>
+        /// Write required string property.
+        /// </summary>
+        /// <param name="writer">The writer.</param>
+        /// <param name="name">The property name.</param>
+        /// <param name="value">The property value.</param>
+        public static void WriteRequiredProperty(this IOpenApiWriter writer, string name, string value)
+        {
+            CheckArguments(writer, name);
+            writer.WritePropertyName(name);
+            writer.WriteValue(value);
+        }
+
         /// <summary>
         /// Write a boolean property.
         /// </summary>