fix: open API link reference proxy design pattern implementation

src/Microsoft.OpenApi.Hidi/StatsVisitor.cs

@@ -62,7 +62,7 @@ public override void Visit(OpenApiOperation operation)
 
         public int LinkCount { get; set; }
 
-        public override void Visit(OpenApiLink link)
+        public override void Visit(IOpenApiLink link)
         {
             LinkCount++;
         }

src/Microsoft.OpenApi.Workbench/StatsVisitor.cs

@@ -62,7 +62,7 @@ public override void Visit(OpenApiOperation operation)
 
         public int LinkCount { get; set; }
 
-        public override void Visit(OpenApiLink link)
+        public override void Visit(IOpenApiLink link)
         {
             LinkCount++;
         }

src/Microsoft.OpenApi/Models/Interfaces/IOpenApiLink.cs

@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+using Microsoft.OpenApi.Interfaces;
+
+namespace Microsoft.OpenApi.Models.Interfaces;
+
+/// <summary>
+/// Defines the base properties for the link object.
+/// This interface is provided for type assertions but should not be implemented by package consumers beyond automatic mocking.
+/// </summary>
+public interface IOpenApiLink : IOpenApiDescribedElement, IOpenApiSerializable, IOpenApiReadOnlyExtensible
+{
+    /// <summary>
+    /// A relative or absolute reference to an OAS operation.
+    /// This field is mutually exclusive of the operationId field, and MUST point to an Operation Object.
+    /// </summary>
+    public string OperationRef { get; }
+
+    /// <summary>
+    /// The name of an existing, resolvable OAS operation, as defined with a unique operationId.
+    /// This field is mutually exclusive of the operationRef field.
+    /// </summary>
+    public string OperationId { get; }
+
+    /// <summary>
+    /// A map representing parameters to pass to an operation as specified with operationId or identified via operationRef.
+    /// </summary>
+    public IDictionary<string, RuntimeExpressionAnyWrapper> Parameters { get; }
+
+    /// <summary>
+    /// A literal value or {expression} to use as a request body when calling the target operation.
+    /// </summary>
+    public RuntimeExpressionAnyWrapper RequestBody { get; }
+    /// <summary>
+    /// A server object to be used by the target operation.
+    /// </summary>
+    public OpenApiServer Server { get; }
+}

src/Microsoft.OpenApi/Models/OpenApiComponents.cs

@@ -56,9 +56,9 @@ public class OpenApiComponents : IOpenApiSerializable, IOpenApiExtensible
             new Dictionary<string, OpenApiSecurityScheme>();
 
         /// <summary>
-        /// An object to hold reusable <see cref="OpenApiLink"/> Objects.
+        /// An object to hold reusable <see cref="IOpenApiLink"/> Objects.
         /// </summary>
-        public IDictionary<string, OpenApiLink>? Links { get; set; } = new Dictionary<string, OpenApiLink>();
+        public IDictionary<string, IOpenApiLink>? Links { get; set; } = new Dictionary<string, IOpenApiLink>();
 
         /// <summary>
         /// An object to hold reusable <see cref="OpenApiCallback"/> Objects.
@@ -92,7 +92,7 @@ public OpenApiComponents(OpenApiComponents? components)
             RequestBodies = components?.RequestBodies != null ? new Dictionary<string, OpenApiRequestBody>(components.RequestBodies) : null;
             Headers = components?.Headers != null ? new Dictionary<string, IOpenApiHeader>(components.Headers) : null;
             SecuritySchemes = components?.SecuritySchemes != null ? new Dictionary<string, OpenApiSecurityScheme>(components.SecuritySchemes) : null;
-            Links = components?.Links != null ? new Dictionary<string, OpenApiLink>(components.Links) : null;
+            Links = components?.Links != null ? new Dictionary<string, IOpenApiLink>(components.Links) : null;
             Callbacks = components?.Callbacks != null ? new Dictionary<string, IOpenApiCallback>(components.Callbacks) : null;
             PathItems = components?.PathItems != null ? new Dictionary<string, OpenApiPathItem>(components.PathItems) : null;
             Extensions = components?.Extensions != null ? new Dictionary<string, IOpenApiExtension>(components.Extensions) : null;

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -604,7 +604,7 @@ public bool AddComponent<T>(string id, T componentToRegister)
                     Components.RequestBodies.Add(id, openApiRequestBody);
                     break;
                 case OpenApiLink openApiLink:
-                    Components.Links ??= new Dictionary<string, OpenApiLink>();
+                    Components.Links ??= new Dictionary<string, IOpenApiLink>();
                     Components.Links.Add(id, openApiLink);
                     break;
                 case OpenApiCallback openApiCallback:

src/Microsoft.OpenApi/Models/OpenApiLink.cs

@@ -4,62 +4,36 @@
 using System;
 using System.Collections.Generic;
 using Microsoft.OpenApi.Interfaces;
+using Microsoft.OpenApi.Models.Interfaces;
 using Microsoft.OpenApi.Writers;
 
 namespace Microsoft.OpenApi.Models
 {
     /// <summary>
     /// Link Object.
     /// </summary>
-    public class OpenApiLink : IOpenApiReferenceable, IOpenApiExtensible
+    public class OpenApiLink : IOpenApiReferenceable, IOpenApiExtensible, IOpenApiLink
     {
-        /// <summary>
-        /// A relative or absolute reference to an OAS operation.
-        /// This field is mutually exclusive of the operationId field, and MUST point to an Operation Object.
-        /// </summary>
-        public virtual string OperationRef { get; set; }
+        /// <inheritdoc/>
+        public string OperationRef { get; set; }
 
-        /// <summary>
-        /// The name of an existing, resolvable OAS operation, as defined with a unique operationId.
-        /// This field is mutually exclusive of the operationRef field.
-        /// </summary>
-        public virtual string OperationId { get; set; }
+        /// <inheritdoc/>
+        public string OperationId { get; set; }
 
-        /// <summary>
-        /// A map representing parameters to pass to an operation as specified with operationId or identified via operationRef.
-        /// </summary>
-        public virtual Dictionary<string, RuntimeExpressionAnyWrapper> Parameters { get; set; } =
-            new();
+        /// <inheritdoc/>
+        public IDictionary<string, RuntimeExpressionAnyWrapper> Parameters { get; set; } = new Dictionary<string, RuntimeExpressionAnyWrapper>();
 
-        /// <summary>
-        /// A literal value or {expression} to use as a request body when calling the target operation.
-        /// </summary>
-        public virtual RuntimeExpressionAnyWrapper RequestBody { get; set; }
-
-        /// <summary>
-        /// A description of the link.
-        /// </summary>
-        public virtual string Description { get; set; }
-
-        /// <summary>
-        /// A server object to be used by the target operation.
-        /// </summary>
-        public virtual OpenApiServer Server { get; set; }
+        /// <inheritdoc/>
+        public RuntimeExpressionAnyWrapper RequestBody { get; set; }
 
-        /// <summary>
-        /// This object MAY be extended with Specification Extensions.
-        /// </summary>
-        public virtual IDictionary<string, IOpenApiExtension> Extensions { get; set; } = new Dictionary<string, IOpenApiExtension>();
+        /// <inheritdoc/>
+        public string Description { get; set; }
 
-        /// <summary>
-        /// Indicates if object is populated with data or is just a reference to the data
-        /// </summary>
-        public virtual bool UnresolvedReference { get; set; }
+        /// <inheritdoc/>
+        public OpenApiServer Server { get; set; }
 
-        /// <summary>
-        /// Reference pointer.
-        /// </summary>
-        public OpenApiReference Reference { get; set; }
+        /// <inheritdoc/>
+        public IDictionary<string, IOpenApiExtension> Extensions { get; set; } = new Dictionary<string, IOpenApiExtension>();
 
         /// <summary>
         /// Parameterless constructor
@@ -69,36 +43,31 @@ public OpenApiLink() { }
         /// <summary>
         /// Initializes a copy of an <see cref="OpenApiLink"/> object
         /// </summary>
-        public OpenApiLink(OpenApiLink link)
+        public OpenApiLink(IOpenApiLink link)
         {
-            OperationRef = link?.OperationRef ?? OperationRef;
-            OperationId = link?.OperationId ?? OperationId;
-            Parameters = link?.Parameters != null ? new(link?.Parameters) : null;
-            RequestBody = link?.RequestBody != null ? new(link?.RequestBody) : null;
-            Description = link?.Description ?? Description;
-            Server = link?.Server != null ? new(link?.Server) : null;
-            Extensions = link?.Extensions != null ? new Dictionary<string, IOpenApiExtension>(link.Extensions) : null;
-            UnresolvedReference = link?.UnresolvedReference ?? UnresolvedReference;
-            Reference = link?.Reference != null ? new(link?.Reference) : null;
+            Utils.CheckArgumentNull(link);
+            OperationRef = link.OperationRef ?? OperationRef;
+            OperationId = link.OperationId ?? OperationId;
+            Parameters = link.Parameters != null ? new Dictionary<string, RuntimeExpressionAnyWrapper>(link.Parameters) : null;
+            RequestBody = link.RequestBody != null ? new(link.RequestBody) : null;
+            Description = link.Description ?? Description;
+            Server = link.Server != null ? new(link.Server) : null;
+            Extensions = link.Extensions != null ? new Dictionary<string, IOpenApiExtension>(link.Extensions) : null;
         }
 
-        /// <summary>
-        /// Serialize <see cref="OpenApiLink"/> to Open Api v3.1
-        /// </summary>
-        public virtual void SerializeAsV31(IOpenApiWriter writer)
+        /// <inheritdoc/>
+        public void SerializeAsV31(IOpenApiWriter writer)
         {
             SerializeInternal(writer, (writer, element) => element.SerializeAsV31(writer));
         }
 
-        /// <summary>
-        /// Serialize <see cref="OpenApiLink"/> to Open Api v3.0
-        /// </summary>
-        public virtual void SerializeAsV3(IOpenApiWriter writer)
+        /// <inheritdoc/>
+        public void SerializeAsV3(IOpenApiWriter writer)
         {
             SerializeInternal(writer, (writer, element) => element.SerializeAsV3(writer));
         }
 
-        internal virtual void SerializeInternal(IOpenApiWriter writer, Action<IOpenApiWriter, IOpenApiSerializable> callback)
+        internal void SerializeInternal(IOpenApiWriter writer, Action<IOpenApiWriter, IOpenApiSerializable> callback)
         {
             Utils.CheckArgumentNull(writer);
 
@@ -128,9 +97,7 @@ internal virtual void SerializeInternal(IOpenApiWriter writer, Action<IOpenApiWr
             writer.WriteEndObject();
         }
 
-        /// <summary>
-        /// Serialize <see cref="OpenApiLink"/> to Open Api v2.0
-        /// </summary>
+        /// <inheritdoc/>
         public void SerializeAsV2(IOpenApiWriter writer)
         {
             // Link object does not exist in V2.

src/Microsoft.OpenApi/Models/OpenApiResponse.cs

@@ -36,7 +36,7 @@
         /// The key of the map is a short name for the link,
         /// following the naming constraints of the names for Component Objects.
         /// </summary>
-        public virtual IDictionary<string, OpenApiLink> Links { get; set; } = new Dictionary<string, OpenApiLink>();
+        public virtual IDictionary<string, IOpenApiLink> Links { get; set; } = new Dictionary<string, IOpenApiLink>();
 
         /// <summary>
         /// This object MAY be extended with Specification Extensions.
@@ -66,7 +66,7 @@
             Description = response?.Description ?? Description;
             Headers = response?.Headers != null ? new Dictionary<string, IOpenApiHeader>(response.Headers) : null;
             Content = response?.Content != null ? new Dictionary<string, OpenApiMediaType>(response.Content) : null;
-            Links = response?.Links != null ? new Dictionary<string, OpenApiLink>(response.Links) : null;
+            Links = response?.Links != null ? new Dictionary<string, IOpenApiLink>(response.Links) : null;
             Extensions = response?.Extensions != null ? new Dictionary<string, IOpenApiExtension>(response.Extensions) : null;
             UnresolvedReference = response?.UnresolvedReference ?? UnresolvedReference;
             Reference = response?.Reference != null ? new(response?.Reference) : null;

src/Microsoft.OpenApi/Models/References/OpenApiCallbackReference.cs

@@ -69,8 +69,8 @@ public OpenApiCallbackReference(string referenceId, OpenApiDocument hostDocument
         public OpenApiCallbackReference(OpenApiCallbackReference callback)
         {
             Utils.CheckArgumentNull(callback);
-            Reference = callback?.Reference != null ? new(callback.Reference) : null;
-            UnresolvedReference = callback?.UnresolvedReference ?? false;
+            Reference = callback.Reference != null ? new(callback.Reference) : null;
+            UnresolvedReference = callback.UnresolvedReference;
         }
 
         internal OpenApiCallbackReference(OpenApiCallback target, string referenceId)

src/Microsoft.OpenApi/Models/References/OpenApiExampleReference.cs

@@ -67,8 +67,8 @@ public OpenApiExampleReference(string referenceId, OpenApiDocument hostDocument,
         public OpenApiExampleReference(OpenApiExampleReference example)
         {
             Utils.CheckArgumentNull(example);
-            Reference = example?.Reference != null ? new(example.Reference) : null;
-            UnresolvedReference = example?.UnresolvedReference ?? false;
+            Reference = example.Reference != null ? new(example.Reference) : null;
+            UnresolvedReference = example.UnresolvedReference;
             //no need to copy summary and description as if they are not overridden, they will be fetched from the target
             //if they are, the reference copy will handle it
         }