Refactor and clean up code

Author: MaggieKimani1

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

@@ -73,47 +73,35 @@ private static void ProcessProduces(MapNode mapNode, OpenApiResponse response, P
             }
 
             var produces = context.GetFromTempStorage<List<string>>(TempStorageKeys.OperationProduces)
-                ?? context.GetFromTempStorage<List<string>>(TempStorageKeys.GlobalProduces);
+                ?? context.GetFromTempStorage<List<string>>(TempStorageKeys.GlobalProduces)
+                ?? new List<string> { "application/octet-stream" };
 
-            if (produces != null)
+            var schema = context.GetFromTempStorage<OpenApiSchema>(TempStorageKeys.ResponseSchema, response);
+
+            foreach (var produce in produces)
             {
-                var schema = context.GetFromTempStorage<OpenApiSchema>(TempStorageKeys.ResponseSchema, response);
 
-                if (produces.Count == 0 && schema != null)
+                if (response.Content.TryGetValue(produce, out var produceValue)) 
                 {
-                    var mediaType = new OpenApiMediaType
+                    if (schema != null)
                     {
-                        Schema = schema
-                    };
-
-                    response.Content.Add("application/octet-stream", mediaType);
+                        produceValue.Schema = schema;
+                        ProcessAnyFields(mapNode, produceValue, _mediaTypeAnyFields);
+                    }
                 }
-
-                foreach (var produce in produces)
+                else
                 {
-
-                    if (response.Content.TryGetValue(produce, out var produceValue)) 
-                    {
-                        if (schema != null)
-                        {
-                            produceValue.Schema = schema;
-                            ProcessAnyFields(mapNode, produceValue, _mediaTypeAnyFields);
-                        }
-                    }
-                    else
+                    var mediaType = new OpenApiMediaType
                     {
-                        var mediaType = new OpenApiMediaType
-                        {
-                            Schema = schema
-                        };
+                        Schema = schema
+                    };
 
-                        response.Content.Add(produce, mediaType);
-                    }
+                    response.Content.Add(produce, mediaType);
                 }
-
-                context.SetTempStorage(TempStorageKeys.ResponseSchema, null, response);
-                context.SetTempStorage(TempStorageKeys.ResponseProducesSet, true, response);
             }
+
+            context.SetTempStorage(TempStorageKeys.ResponseSchema, null, response);
+            context.SetTempStorage(TempStorageKeys.ResponseProducesSet, true, response);
         }
 
         private static void LoadExamples(OpenApiResponse response, ParseNode node)

src/Microsoft.OpenApi/Services/OpenApiReferenceResolver.cs

@@ -256,7 +256,7 @@ private void ResolveTags(IList<OpenApiTag> tags)
 
         private T ResolveReference<T>(OpenApiReference reference) where T : class, IOpenApiReferenceable, new()
         {
-            if (string.IsNullOrEmpty(reference.ExternalResource))
+            if (string.IsNullOrEmpty(reference?.ExternalResource))
             {
                 try
                 {

test/Microsoft.OpenApi.Readers.Tests/V2Tests/OpenApiDocumentTests.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;
@@ -163,45 +163,25 @@ public void ShouldParseProducesInAnyOrder()
                 var reader = new OpenApiStreamReader();
                 var doc = reader.Read(stream, out var diagnostic);
 
-                var successSchema = new OpenApiSchema()
+                var okSchema = new OpenApiSchema()
                 {
-                    Type = "array",
                     Reference = new OpenApiReference
                     {
                         Type = ReferenceType.Schema,
                         Id = "Item",
                         HostDocument = doc
                     },
-                    Items = new OpenApiSchema()
+                    Properties = new Dictionary<string, OpenApiSchema>()
                     {
-                        Reference = new OpenApiReference()
-                        {
-                            Type = ReferenceType.Schema,
-                            Id = "Item",
-                            HostDocument = doc
+                        { "id", new OpenApiSchema()
+                            {
+                                Type = "string",
+                                Description = "Item identifier."
+                            }
                         }
                     }
                 };
 
-                var okSchema = new OpenApiSchema()
-                {
-                    Reference = new OpenApiReference
-                    {
-                        Type = ReferenceType.Schema,
-                        Id = "Item",
-                        HostDocument = doc
-                    },
-                    Properties = new Dictionary<string, OpenApiSchema>()
-                                                    {
-                                                        { "id", new OpenApiSchema()
-                                                            {
-                                                                Type = "string",
-                                                                Description = "Item identifier."
-                                                            }
-                                                        }
-                                                    }
-                };
-
                 var errorSchema = new OpenApiSchema()
                 {
                     Reference = new OpenApiReference
@@ -211,24 +191,24 @@ public void ShouldParseProducesInAnyOrder()
                         HostDocument = doc
                     },
                     Properties = new Dictionary<string, OpenApiSchema>()
-                                                    {
-                                                        { "code", new OpenApiSchema()
-                                                            {
-                                                                Type = "integer",
-                                                                Format = "int32"
-                                                            }
-                                                        },
-                                                        { "message", new OpenApiSchema()
-                                                            {
-                                                                Type = "string"
-                                                            }
-                                                        },
-                                                        { "fields", new OpenApiSchema()
-                                                            {
-                                                                Type = "string"
-                                                            }
-                                                        }
-                                                    }
+                    {
+                        { "code", new OpenApiSchema()
+                            {
+                                Type = "integer",
+                                Format = "int32"
+                            }
+                        },
+                        { "message", new OpenApiSchema()
+                            {
+                                Type = "string"
+                            }
+                        },
+                        { "fields", new OpenApiSchema()
+                            {
+                                Type = "string"
+                            }
+                        }
+                    }
                 };
 
                 var okMediaType = new OpenApiMediaType