Update src/Microsoft.OpenApi/Reader/V2/OpenApiSecurityRequirementDeserializer.cs

Co-authored-by: Vincent Biret <[email protected]>

Author: MaggieKimani1

src/Microsoft.OpenApi/Reader/V2/OpenApiSecurityRequirementDeserializer.cs

@@ -28,8 +28,7 @@ public static OpenApiSecurityRequirement LoadSecurityRequirement(ParseNode node,
                     property.Name);
 
                 var scopes = property.Value.CreateSimpleList((n2, p) => n2.GetScalarValue(), hostDocument)
-                    .Where(scope => scope != null)
-                    .Cast<string>()
+                    .OfType<string>()
                     .ToList();
 
                 if (scheme != null)