Add resolving references to child properties of a Header fragment

Author: simon-pearson-lmk

src/Microsoft.OpenApi/Extensions/OpenApiReferencableExtensions.cs

@@ -30,6 +30,10 @@ public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable
                 return element;
             try
             {
+                if (element.GetType() == typeof(OpenApiHeader))
+                {
+                    return ResolveReferenceOnHeaderElement((OpenApiHeader)element, jsonPointer);
+                }
                 if (element.GetType() == typeof(OpenApiParameter))
                 {
                     return ResolveReferenceOnParameterElement((OpenApiParameter)element, jsonPointer);
@@ -42,6 +46,24 @@ public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable
             throw new NotImplementedException();
         }
 
+        private static IOpenApiReferenceable ResolveReferenceOnHeaderElement(OpenApiHeader headerElement, string jsonPointer)
+        {
+            var jsonPointerTokens = jsonPointer.Split('/');
+            var propertyName = jsonPointerTokens.ElementAtOrDefault(1);
+            switch (propertyName)
+            {
+                case OpenApiConstants.Schema:
+                    return headerElement.Schema;
+                case OpenApiConstants.Examples:
+                    {
+                        var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
+                        return headerElement.Examples[mapKey];
+                    }
+                default:
+                    throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
+            }
+        }
+
         private static IOpenApiReferenceable ResolveReferenceOnParameterElement(OpenApiParameter parameterElement, string jsonPointer)
         {
             var jsonPointerTokens = jsonPointer.Split('/');

test/Microsoft.OpenApi.Tests/Workspaces/OpenApiReferencableTests.cs

@@ -18,7 +18,14 @@ public class OpenApiReferencableTests
         private static readonly OpenApiCallback _callbackFragment = new OpenApiCallback();
         private static readonly OpenApiExample _exampleFragment = new OpenApiExample();
         private static readonly OpenApiLink _linkFragment = new OpenApiLink();
-        private static readonly OpenApiHeader _headerFragment = new OpenApiHeader();
+        private static readonly OpenApiHeader _headerFragment = new OpenApiHeader()
+        {
+            Schema = new OpenApiSchema(),
+            Examples = new Dictionary<string, OpenApiExample>
+            {
+                { "example1", new OpenApiExample() }
+            }
+        };
         private static readonly OpenApiParameter _parameterFragment = new OpenApiParameter
         {
             Schema = new OpenApiSchema(),
@@ -40,6 +47,8 @@ public class OpenApiReferencableTests
             new object[] { _exampleFragment, "/", _exampleFragment },
             new object[] { _linkFragment, "/", _linkFragment },
             new object[] { _headerFragment, "/", _headerFragment },
+            new object[] { _headerFragment, "/schema", _headerFragment.Schema },
+            new object[] { _headerFragment, "/examples/example1", _headerFragment.Examples["example1"] },
             new object[] { _parameterFragment, "/", _parameterFragment },
             new object[] { _parameterFragment, "/schema", _parameterFragment.Schema },
             new object[] { _parameterFragment, "/examples/example1", _parameterFragment.Examples["example1"] },