diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/ApiResponse.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/ApiResponse.cs
index c5937000ae8..d5ddd110bd9 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/ApiResponse.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/ApiResponse.cs
@@ -73,7 +73,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((ApiResponse)obj);
         }
@@ -85,7 +85,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(ApiResponse other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return 
diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Category.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Category.cs
index 5c58d5fd461..44b87698f26 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Category.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Category.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((Category)obj);
         }
@@ -78,7 +78,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(Category other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return 
diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Order.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Order.cs
index 4f21cb7268d..673983d6bce 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Order.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Order.cs
@@ -122,7 +122,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((Order)obj);
         }
@@ -134,7 +134,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(Order other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return 
diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Pet.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Pet.cs
index d3e6dbc5dcd..927a9087b49 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Pet.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Pet.cs
@@ -124,7 +124,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((Pet)obj);
         }
@@ -136,7 +136,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(Pet other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return 
diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Tag.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Tag.cs
index cc9916d4392..f3f652c0e4e 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Tag.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/Tag.cs
@@ -66,7 +66,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((Tag)obj);
         }
@@ -78,7 +78,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(Tag other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return 
diff --git a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/User.cs b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/User.cs
index 2fb42e7ab8d..df458f9bbd2 100644
--- a/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/User.cs
+++ b/samples/server/petstore/aspnetcore/src/Org.OpenAPITools/Models/User.cs
@@ -109,7 +109,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (obj is null) return false;
             if (ReferenceEquals(this, obj)) return true;
             return obj.GetType() == GetType() && Equals((User)obj);
         }
@@ -121,7 +121,7 @@ namespace Org.OpenAPITools.Models
         /// <returns>Boolean</returns>
         public bool Equals(User other)
         {
-            if (ReferenceEquals(null, other)) return false;
+            if (other is null) return false;
             if (ReferenceEquals(this, other)) return true;
 
             return