implement metadata

Author: VisualBean

src/LEGO.AsyncAPI/Models/Avro/AvroRecord.cs

@@ -3,28 +3,58 @@
 namespace LEGO.AsyncAPI.Models
 {
     using System.Collections.Generic;
+    using System.Linq;
     using LEGO.AsyncAPI.Writers;
 
     public class AvroRecord : AvroFieldType
     {
         public string Type { get; } = "record";
 
+        /// <summary>
+        /// The name of the schema. Required for named types. See <a href="https://avro.apache.org/docs/1.9.0/spec.html#names">Avro Names</a>.
+        /// </summary>
         public string Name { get; set; }
 
-        public string Doc { get; set; }
+        /// <summary>
+        /// The namespace of the schema. Useful for named types to avoid name conflicts.
+        /// </summary>
+        public string? Namespace { get; set; }
+
+        /// <summary>
+        /// Documentation for the schema.
+        /// </summary>
+        public string? Doc { get; set; }
 
         public IList<string> Aliases { get; set; } = new List<string>();
 
         public IList<AvroField> Fields { get; set; } = new List<AvroField>();
 
+        public IDictionary<string, AvroFieldType> Metadata { get; set; } = new Dictionary<string, AvroFieldType>();
+
         public override void SerializeV2(IAsyncApiWriter writer)
         {
             writer.WriteStartObject();
             writer.WriteOptionalProperty("type", this.Type);
             writer.WriteRequiredProperty("name", this.Name);
+            writer.WriteRequiredProperty("namespace", this.Namespace);
             writer.WriteOptionalProperty("doc", this.Doc);
             writer.WriteOptionalCollection("aliases", this.Aliases, (w, s) => w.WriteValue(s));
             writer.WriteRequiredCollection("fields", this.Fields, (w, s) => s.SerializeV2(w));
+            if (this.Metadata.Any())
+            {
+                foreach (var item in this.Metadata)
+                {
+                    writer.WritePropertyName(item.Key);
+                    if (item.Value == null)
+                    {
+                        writer.WriteNull();
+                    }
+                    else
+                    {
+                        item.Value.SerializeV2(writer);
+                    }
+                }
+            }
             writer.WriteEndObject();
         }
     }