feat: makes document optional

Signed-off-by: Vincent Biret <vibiret@microsoft.com>

Author: baywet

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -26,6 +26,13 @@ namespace Microsoft.OpenApi.Models
     /// </summary>
     public class OpenApiDocument : IOpenApiSerializable, IOpenApiExtensible, IOpenApiAnnotatable
     {
+        /// <summary>
+        /// Register components in the document to the workspace
+        /// </summary>
+        public void RegisterComponents()
+        {
+            Workspace?.RegisterComponents(this);
+        }
         /// <summary>
         /// Related workspace containing components that are referenced in a document
         /// </summary>

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

@@ -10,16 +10,11 @@ namespace Microsoft.OpenApi.Models.References;
 /// <typeparam name="V">The interface type for the model.</typeparam>
 public abstract class BaseOpenApiReferenceHolder<T, V> : IOpenApiReferenceHolder<T, V> where T : class, IOpenApiReferenceable, V where V : IOpenApiSerializable
 {
-    /// <summary>
-    /// The resolved target object. This should remain readonly, otherwise mutating the reference will have side effects.
-    /// </summary>
-    protected readonly T _target;
     /// <inheritdoc/>
     public virtual T Target
     {
         get
         {
-            if (_target is not null) return _target;
             return Reference.HostDocument?.ResolveReferenceTo<T>(Reference);
         }
     }
@@ -34,17 +29,6 @@ protected BaseOpenApiReferenceHolder(BaseOpenApiReferenceHolder<T, V> source)
         //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
     }
-    private protected BaseOpenApiReferenceHolder(T target, string referenceId, ReferenceType referenceType)
-    {
-        Utils.CheckArgumentNull(target);
-        _target = target;
-
-        Reference = new OpenApiReference()
-        {
-            Id = referenceId,
-            Type = referenceType,
-        };
-    }
     /// <summary>
     /// Constructor initializing the reference object.
     /// </summary>
@@ -56,9 +40,11 @@ private protected BaseOpenApiReferenceHolder(T target, string referenceId, Refer
     /// 1. a absolute/relative file path, for example:  ../commons/pet.json
     /// 2. a Url, for example: http://localhost/pet.json
     /// </param>
-    protected BaseOpenApiReferenceHolder(string referenceId, OpenApiDocument hostDocument, ReferenceType referenceType, string externalResource = null)
+    protected BaseOpenApiReferenceHolder(string referenceId, OpenApiDocument hostDocument, ReferenceType referenceType, string externalResource)
     {
         Utils.CheckArgumentNullOrEmpty(referenceId);
+        // we're not checking for null hostDocument as it's optional and can be set via additional methods by a walker
+        // this way object initialization of a whole document is supported
 
         Reference = new OpenApiReference()
         {

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

@@ -25,7 +25,7 @@ public class OpenApiCallbackReference : BaseOpenApiReferenceHolder<OpenApiCallba
         /// 1. an absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiCallbackReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Callback, externalResource)
+        public OpenApiCallbackReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Callback, externalResource)
         {
         }
         /// <summary>
@@ -37,10 +37,6 @@ private OpenApiCallbackReference(OpenApiCallbackReference callback):base(callbac
 
         }
 
-        internal OpenApiCallbackReference(OpenApiCallback target, string referenceId):base(target, referenceId, ReferenceType.Callback)
-        {
-        }
-
         /// <inheritdoc/>
         public Dictionary<RuntimeExpression, IOpenApiPathItem> PathItems { get => Target?.PathItems; }
 

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

@@ -25,7 +25,7 @@ public class OpenApiExampleReference : BaseOpenApiReferenceHolder<OpenApiExample
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiExampleReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Example, externalResource)
+        public OpenApiExampleReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Example, externalResource)
         {
         }
         /// <summary>
@@ -36,10 +36,6 @@ private OpenApiExampleReference(OpenApiExampleReference example):base(example)
         {
         }
 
-        internal OpenApiExampleReference(OpenApiExample target, string referenceId):base(target, referenceId, ReferenceType.Example)
-        {
-        }
-
         /// <inheritdoc/>
         public string Description
         {

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

@@ -24,7 +24,7 @@ public class OpenApiHeaderReference : BaseOpenApiReferenceHolder<OpenApiHeader,
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiHeaderReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Header, externalResource)
+        public OpenApiHeaderReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Header, externalResource)
         {
         }
 
@@ -36,10 +36,6 @@ private OpenApiHeaderReference(OpenApiHeaderReference header):base(header)
         {
         }
 
-        internal OpenApiHeaderReference(OpenApiHeader target, string referenceId):base(target, referenceId, ReferenceType.Header)
-        {
-        }
-
         /// <inheritdoc/>
         public string Description
         {

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

@@ -24,7 +24,7 @@ public class OpenApiLinkReference : BaseOpenApiReferenceHolder<OpenApiLink, IOpe
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiLinkReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Link, externalResource)
+        public OpenApiLinkReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Link, externalResource)
         {
         }
         /// <summary>
@@ -34,9 +34,6 @@ public OpenApiLinkReference(string referenceId, OpenApiDocument hostDocument, st
         private OpenApiLinkReference(OpenApiLinkReference reference):base(reference)
         {
         }
-        internal OpenApiLinkReference(OpenApiLink target, string referenceId):base(target, referenceId, ReferenceType.Link)
-        {
-        }
 
         /// <inheritdoc/>
         public string Description

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

@@ -23,7 +23,7 @@ public class OpenApiParameterReference : BaseOpenApiReferenceHolder<OpenApiParam
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiParameterReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Parameter, externalResource)
+        public OpenApiParameterReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Parameter, externalResource)
         {
         }
 
@@ -35,10 +35,6 @@ private OpenApiParameterReference(OpenApiParameterReference parameter):base(para
         {
         }
 
-        internal OpenApiParameterReference(OpenApiParameter target, string referenceId):base(target, referenceId, ReferenceType.Parameter)
-        {
-        }
-
         /// <inheritdoc/>
         public string Name { get => Target?.Name; }
 

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

@@ -24,7 +24,7 @@ public class OpenApiPathItemReference : BaseOpenApiReferenceHolder<OpenApiPathIt
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiPathItemReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null): base(referenceId, hostDocument, ReferenceType.PathItem, externalResource)
+        public OpenApiPathItemReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null): base(referenceId, hostDocument, ReferenceType.PathItem, externalResource)
         {
         }
 
@@ -37,10 +37,6 @@ private OpenApiPathItemReference(OpenApiPathItemReference pathItem):base(pathIte
 
         }
 
-        internal OpenApiPathItemReference(OpenApiPathItem target, string referenceId):base(target, referenceId, ReferenceType.PathItem)
-        {
-        }
-
         /// <inheritdoc/>
         public string Summary
         {

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

@@ -25,7 +25,7 @@ public class OpenApiRequestBodyReference : BaseOpenApiReferenceHolder<OpenApiReq
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiRequestBodyReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.RequestBody, externalResource)
+        public OpenApiRequestBodyReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.RequestBody, externalResource)
         {
         }
         /// <summary>
@@ -35,9 +35,6 @@ public OpenApiRequestBodyReference(string referenceId, OpenApiDocument hostDocum
         private OpenApiRequestBodyReference(OpenApiRequestBodyReference openApiRequestBodyReference):base(openApiRequestBodyReference)
         {
 
-        }
-        internal OpenApiRequestBodyReference(OpenApiRequestBody target, string referenceId):base(target, referenceId, ReferenceType.RequestBody)
-        {
         }
 
         /// <inheritdoc/>

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

@@ -23,7 +23,7 @@ public class OpenApiResponseReference : BaseOpenApiReferenceHolder<OpenApiRespon
         /// 1. a absolute/relative file path, for example:  ../commons/pet.json
         /// 2. a Url, for example: http://localhost/pet.json
         /// </param>
-        public OpenApiResponseReference(string referenceId, OpenApiDocument hostDocument, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Response, externalResource)
+        public OpenApiResponseReference(string referenceId, OpenApiDocument hostDocument = null, string externalResource = null):base(referenceId, hostDocument, ReferenceType.Response, externalResource)
         {
         }
         /// <summary>
@@ -35,10 +35,6 @@ private OpenApiResponseReference(OpenApiResponseReference openApiResponseReferen
 
         }
 
-        internal OpenApiResponseReference(OpenApiResponse target, string referenceId):base(target, referenceId, ReferenceType.Response)
-        {
-        }
-
         /// <inheritdoc/>
         public string Description
         {