Fixed security requirement resolution

Author: darrelmiller

src/Microsoft.OpenApi.Readers/Services/OpenApiReferenceResolver.cs

@@ -89,6 +89,24 @@ public override void Visit(OpenApiResponses responses)
             ResolveMap(responses);
         }
 
+        /// <summary>
+        /// Resolve all references to SecuritySchemes
+        /// </summary>
+        /// <param name="securityRequirement"></param>
+        public override void Visit(OpenApiSecurityRequirement securityRequirement)
+        {
+            foreach (var scheme in securityRequirement.Keys.ToList())
+            {
+                ResolveObject(scheme, (resolvedScheme) => {
+                    // If scheme was unresolved
+                    // copy Scopes and remove old unresolved scheme
+                    var scopes = securityRequirement[scheme];
+                    securityRequirement.Remove(scheme);
+                    securityRequirement.Add(resolvedScheme, scopes);
+                });
+            }
+        }
+
         /// <summary>
         /// Resolve all references to links
         /// </summary>

src/Microsoft.OpenApi/Services/OpenApiVisitorBase.cs

@@ -279,6 +279,13 @@ public virtual void Visit(IList<OpenApiTag> openApiTags)
         {
         }
 
+        /// <summary>
+        /// Visits list of <see cref="OpenApiSecurityRequirement"/>
+        /// </summary>
+        public virtual void Visit(IList<OpenApiSecurityRequirement> openApiSecurityRequirements)
+        {
+        }
+        
         /// <summary>
         /// Visits <see cref="IOpenApiExtensible"/>
         /// </summary>

src/Microsoft.OpenApi/Services/OpenApiWalker.cs

@@ -470,10 +470,32 @@ internal void Walk(OpenApiOperation operation)
             Walk(OpenApiConstants.Responses, () => Walk(operation.Responses));
             Walk(OpenApiConstants.Callbacks, () => Walk(operation.Callbacks));
             Walk(OpenApiConstants.Tags, () => Walk(operation.Tags));
-
+            Walk(OpenApiConstants.Security, () => Walk(operation.Security));
             Walk(operation as IOpenApiExtensible);
         }
 
+        /// <summary>
+        /// Visits list of <see cref="OpenApiSecurityRequirement"/>
+        /// </summary>
+        internal void Walk(IList<OpenApiSecurityRequirement> securityRequirements)
+        {
+            if (securityRequirements == null)
+            {
+                return;
+            }
+
+            _visitor.Visit(securityRequirements);
+
+            if (securityRequirements != null)
+            {
+                for (int i = 0; i < securityRequirements.Count; i++)
+                {
+                    Walk(i.ToString(), () => Walk(securityRequirements[i]));
+                }
+            }
+        }
+
+
         /// <summary>
         /// Visits list of <see cref="OpenApiParameter"/>
         /// </summary>