Use static keyword; fix sonarcloud bug

Author: MaggieKimani1

src/Microsoft.OpenApi.Readers/Microsoft.OpenApi.Readers.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0</TargetFrameworks>
+        <LangVersion>9.0</LangVersion>
         <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
         <PackageIconUrl>http://go.microsoft.com/fwlink/?LinkID=288890</PackageIconUrl>
         <PackageProjectUrl>https://github.com/Microsoft/OpenAPI.NET</PackageProjectUrl>

src/Microsoft.OpenApi.Readers/V2/OpenApiV2Deserializer.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
 using System.Collections.Generic;
@@ -29,7 +29,7 @@ private static void ParseMap<T>(
                 return;
             }
 
-            var allFields = fixedFieldMap.Keys.Union(mapNode.Select(x => x.Name));
+            var allFields = fixedFieldMap.Keys.Union(mapNode.Select(static x => x.Name));
             foreach (var propertyNode in allFields)
             {
                 mapNode[propertyNode]?.ParseField(domainObject, fixedFieldMap, patternFieldMap);
@@ -78,16 +78,18 @@ private static void ProcessAnyListFields<T>(
                     var newProperty = new List<IOpenApiAny>();
 
                     mapNode.Context.StartObject(anyListFieldName);
-
-                    var list = anyListFieldMap[anyListFieldName]?.PropertyGetter(domainObject);
-                    if (list != null)
+                    if (anyListFieldMap.TryGetValue(anyListFieldName, out var fieldName))
                     {
-                        foreach (var propertyElement in list)
+                        var list = fieldName.PropertyGetter(domainObject);
+                        if (list != null)
                         {
-                            newProperty.Add(
-                                OpenApiAnyConverter.GetSpecificOpenApiAny(
-                                    propertyElement,
-                                    anyListFieldMap[anyListFieldName].SchemaGetter(domainObject)));
+                            foreach (var propertyElement in list)
+                            {
+                                newProperty.Add(
+                                    OpenApiAnyConverter.GetSpecificOpenApiAny(
+                                        propertyElement,
+                                        anyListFieldMap[anyListFieldName].SchemaGetter(domainObject)));
+                            }
                         }
                     }