feat: enable null reference type support

src/Microsoft.OpenApi.Hidi/Extensions/OpenApiExtensibleExtensions.cs

@@ -14,7 +14,7 @@ internal static class OpenApiExtensibleExtensions
         /// <returns>A <see cref="string"/> value matching the provided extensionKey. Return null when extensionKey is not found. </returns>
         internal static string GetExtension(this IDictionary<string, IOpenApiExtension> extensions, string extensionKey)
         {
-            if (extensions.TryGetValue(extensionKey, out var value) && value is OpenApiAny castValue)
+            if (extensions.TryGetValue(extensionKey, out var value) && value is OpenApiAny castValue && castValue.Node is not null)
             {
                 return castValue.Node.GetValue<string>();
             }

src/Microsoft.OpenApi.Hidi/Formatters/PowerShellFormatter.cs

@@ -53,7 +53,7 @@ public override void Visit(IOpenApiSchema schema)
 
         public override void Visit(IOpenApiPathItem pathItem)
         {
-            if (pathItem.Operations.TryGetValue(OperationType.Put, out var value) &&
+            if (pathItem.Operations is not null && pathItem.Operations.TryGetValue(OperationType.Put, out var value) &&
                 value.OperationId != null)
             {
                 var operationId = value.OperationId;
@@ -149,7 +149,7 @@ private static string RemoveKeyTypeSegment(string operationId, IList<IOpenApiPar
             var segments = operationId.SplitByChar('.');
             foreach (var parameter in parameters)
             {
-                var keyTypeExtension = parameter.Extensions.GetExtension("x-ms-docs-key-type");
+                var keyTypeExtension = parameter.Extensions?.GetExtension("x-ms-docs-key-type");
                 if (keyTypeExtension != null && operationId.Contains(keyTypeExtension, StringComparison.OrdinalIgnoreCase))
                 {
                     segments.Remove(keyTypeExtension);
@@ -178,7 +178,10 @@ private static void ResolveFunctionParameters(IList<IOpenApiParameter> parameter
 
         private void AddAdditionalPropertiesToSchema(IOpenApiSchema schema)
         {
-            if (schema is OpenApiSchema openApiSchema && !_schemaLoop.Contains(schema) && schema.Type.Equals(JsonSchemaType.Object))
+            if (schema is OpenApiSchema openApiSchema 
+                && !_schemaLoop.Contains(schema) 
+                && schema.Type.Equals(JsonSchemaType.Object) 
+                && schema.AdditionalProperties is not null)
             {
                 openApiSchema.AdditionalProperties = new OpenApiSchema() { Type = JsonSchemaType.Object };
 

src/Microsoft.OpenApi.Hidi/OpenApiService.cs

@@ -155,7 +155,7 @@ public static async Task TransformOpenApiDocumentAsync(HidiOptions options, ILog
             return apiDependency;
         }
 
-        private static OpenApiDocument ApplyFilters(HidiOptions options, ILogger logger, ApiDependency? apiDependency, JsonDocument? postmanCollection, OpenApiDocument document)
+        private static OpenApiDocument? ApplyFilters(HidiOptions options, ILogger logger, ApiDependency? apiDependency, JsonDocument? postmanCollection, OpenApiDocument? document)
         {
             Dictionary<string, List<string>> requestUrls;
             if (apiDependency != null)
@@ -191,7 +191,7 @@ private static OpenApiDocument ApplyFilters(HidiOptions options, ILogger logger,
             return document;
         }
 
-        private static async Task WriteOpenApiAsync(HidiOptions options, OpenApiFormat openApiFormat, OpenApiSpecVersion openApiVersion, OpenApiDocument document, ILogger logger, CancellationToken cancellationToken)
+        private static async Task WriteOpenApiAsync(HidiOptions options, OpenApiFormat openApiFormat, OpenApiSpecVersion openApiVersion, OpenApiDocument? document, ILogger logger, CancellationToken cancellationToken)
         {
             using (logger.BeginScope("Output"))
             {
@@ -225,9 +225,9 @@ private static async Task WriteOpenApiAsync(HidiOptions options, OpenApiFormat o
         }
 
         // Get OpenAPI document either from OpenAPI or CSDL
-        private static async Task<OpenApiDocument> GetOpenApiAsync(HidiOptions options, string format, ILogger logger, string? metadataVersion = null, CancellationToken cancellationToken = default)
+        private static async Task<OpenApiDocument?> GetOpenApiAsync(HidiOptions options, string format, ILogger logger, string? metadataVersion = null, CancellationToken cancellationToken = default)
         {
-            OpenApiDocument document;
+            OpenApiDocument? document;
             Stream stream;
 
             if (!string.IsNullOrEmpty(options.Csdl))
@@ -248,7 +248,7 @@ private static async Task<OpenApiDocument> GetOpenApiAsync(HidiOptions options,
 
                     document = await ConvertCsdlToOpenApiAsync(filteredStream ?? stream, format, metadataVersion, options.SettingsConfig, cancellationToken).ConfigureAwait(false);
                     stopwatch.Stop();
-                    logger.LogTrace("{Timestamp}ms: Generated OpenAPI with {Paths} paths.", stopwatch.ElapsedMilliseconds, document.Paths.Count);
+                    logger.LogTrace("{Timestamp}ms: Generated OpenAPI with {Paths} paths.", stopwatch.ElapsedMilliseconds, document?.Paths.Count);
                 }
             }
             else if (!string.IsNullOrEmpty(options.OpenApi))
@@ -262,7 +262,7 @@ private static async Task<OpenApiDocument> GetOpenApiAsync(HidiOptions options,
             return document;
         }
 
-        private static Func<string, OperationType?, OpenApiOperation, bool>? FilterOpenApiDocument(string? filterByOperationIds, string? filterByTags, Dictionary<string, List<string>> requestUrls, OpenApiDocument document, ILogger logger)
+        private static Func<string, OperationType?, OpenApiOperation, bool>? FilterOpenApiDocument(string? filterByOperationIds, string? filterByTags, Dictionary<string, List<string>> requestUrls, OpenApiDocument? document, ILogger logger)
         {
             Func<string, OperationType?, OpenApiOperation, bool>? predicate = null;
 
@@ -376,7 +376,7 @@ private static MemoryStream ApplyFilterToCsdl(Stream csdlStream, string entitySe
 
             if (result is null) return null;
 
-            return result.Diagnostic.Errors.Count == 0;
+            return result.Diagnostic?.Errors.Count == 0;
         }
 
         private static async Task<ReadResult> ParseOpenApiAsync(string openApiFile, bool inlineExternal, ILogger logger, Stream stream, CancellationToken cancellationToken = default)
@@ -411,7 +411,7 @@ private static async Task<ReadResult> ParseOpenApiAsync(string openApiFile, bool
         /// </summary>
         /// <param name="csdl">The CSDL stream.</param>
         /// <returns>An OpenAPI document.</returns>
-        public static async Task<OpenApiDocument> ConvertCsdlToOpenApiAsync(Stream csdl, string format, string? metadataVersion = null, IConfiguration? settings = null, CancellationToken token = default)
+        public static async Task<OpenApiDocument?> ConvertCsdlToOpenApiAsync(Stream csdl, string format, string? metadataVersion = null, IConfiguration? settings = null, CancellationToken token = default)
         {
             using var reader = new StreamReader(csdl);
             var csdlText = await reader.ReadToEndAsync(token).ConfigureAwait(false);
@@ -429,7 +429,7 @@ public static async Task<OpenApiDocument> ConvertCsdlToOpenApiAsync(Stream csdl,
         /// </summary>
         /// <param name="document"> The converted OpenApiDocument.</param>
         /// <returns> A valid OpenApiDocument instance.</returns>
-        public static OpenApiDocument FixReferences(OpenApiDocument document, string format)
+        public static OpenApiDocument? FixReferences(OpenApiDocument document, string format)
         {
             // This method is only needed because the output of ConvertToOpenApi isn't quite a valid OpenApiDocument instance.
             // So we write it out, and read it back in again to fix it up.
@@ -648,7 +648,7 @@ private static string GetInputPathExtension(string? openapi = null, string? csdl
         private static void LogErrors(ILogger logger, ReadResult result)
         {
             var context = result.Diagnostic;
-            if (context.Errors.Count != 0)
+            if (context is not null && context.Errors.Count != 0)
             {
                 using (logger.BeginScope("Detected errors"))
                 {
@@ -660,11 +660,11 @@ private static void LogErrors(ILogger logger, ReadResult result)
             }
         }
 
-        internal static void WriteTreeDocumentAsMarkdown(string openapiUrl, OpenApiDocument document, StreamWriter writer)
+        internal static void WriteTreeDocumentAsMarkdown(string openapiUrl, OpenApiDocument? document, StreamWriter writer)
         {
             var rootNode = OpenApiUrlTreeNode.Create(document, "main");
 
-            writer.WriteLine("# " + document.Info.Title);
+            writer.WriteLine("# " + document?.Info.Title);
             writer.WriteLine();
             writer.WriteLine("API Description: " + openapiUrl);
 
@@ -681,7 +681,7 @@ internal static void WriteTreeDocumentAsMarkdown(string openapiUrl, OpenApiDocum
             writer.WriteLine("```");
         }
 
-        internal static void WriteTreeDocumentAsHtml(string sourceUrl, OpenApiDocument document, StreamWriter writer, bool asHtmlFile = false)
+        internal static void WriteTreeDocumentAsHtml(string sourceUrl, OpenApiDocument? document, StreamWriter writer, bool asHtmlFile = false)
         {
             var rootNode = OpenApiUrlTreeNode.Create(document, "main");
 
@@ -700,7 +700,7 @@ internal static void WriteTreeDocumentAsHtml(string sourceUrl, OpenApiDocument d
                 </style>
                 <body>
                 """);
-            writer.WriteLine("<h1>" + document.Info.Title + "</h1>");
+            writer.WriteLine("<h1>" + document?.Info.Title + "</h1>");
             writer.WriteLine();
             writer.WriteLine($"<h3> API Description: <a href='{sourceUrl}'>{sourceUrl}</a></h3>");
 
@@ -771,9 +771,13 @@ internal static async Task PluginManifestAsync(HidiOptions options, ILogger logg
             await WriteOpenApiAsync(options, OpenApiFormat.Json, OpenApiSpecVersion.OpenApi3_1, document, logger, cancellationToken).ConfigureAwait(false);
 
             // Create OpenAIPluginManifest from ApiDependency and OpenAPI document
-            var manifest = new OpenAIPluginManifest(document.Info?.Title ?? "Title", document.Info?.Title ?? "Title", "https://go.microsoft.com/fwlink/?LinkID=288890", document.Info?.Contact?.Email ?? "placeholder@contoso.com", document.Info?.License?.Url.ToString() ?? "https://placeholderlicenseurl.com")
+            var manifest = new OpenAIPluginManifest(document?.Info.Title ?? "Title",
+                                                    document?.Info.Title ?? "Title",
+                                                    "https://go.microsoft.com/fwlink/?LinkID=288890",
+                                                    document?.Info?.Contact?.Email ?? "placeholder@contoso.com",
+                                                    document?.Info?.License?.Url?.ToString() ?? "https://placeholderlicenseurl.com")
             {
-                DescriptionForHuman = document.Info?.Description ?? "Description placeholder",
+                DescriptionForHuman = document?.Info.Description ?? "Description placeholder",
                 Api = new("openapi", "./openapi.json"),
                 Auth = new ManifestNoAuth(),
             };

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

@@ -11,6 +11,7 @@
         <!-- https://github.com/dotnet/sourcelink/blob/main/docs/README.md#embeduntrackedsources -->
         <EmbedUntrackedSources>true</EmbedUntrackedSources>
         <NoWarn>NU5048</NoWarn>
+        <Nullable>enable</Nullable>
         <PackageReadmeFile>README.md</PackageReadmeFile>
     </PropertyGroup>
 

src/Microsoft.OpenApi.Readers/OpenApiYamlReader.cs

@@ -84,11 +84,11 @@ public static ReadResult Read(JsonNode jsonNode, OpenApiReaderSettings settings)
         }
 
         /// <inheritdoc/>
-        public T ReadFragment<T>(MemoryStream input,
+        public T? ReadFragment<T>(MemoryStream input,
                                  OpenApiSpecVersion version,
                                  OpenApiDocument openApiDocument,
                                  out OpenApiDiagnostic diagnostic,
-                                 OpenApiReaderSettings settings = null) where T : IOpenApiElement
+                                 OpenApiReaderSettings? settings = null) where T : IOpenApiElement
         {
             if (input is null) throw new ArgumentNullException(nameof(input));
             JsonNode jsonNode;
@@ -110,7 +110,7 @@ public T ReadFragment<T>(MemoryStream input,
         }
 
         /// <inheritdoc/>
-        public static T ReadFragment<T>(JsonNode input, OpenApiSpecVersion version, OpenApiDocument openApiDocument, out OpenApiDiagnostic diagnostic, OpenApiReaderSettings settings = null) where T : IOpenApiElement
+        public static T ReadFragment<T>(JsonNode input, OpenApiSpecVersion version, OpenApiDocument openApiDocument, out OpenApiDiagnostic diagnostic, OpenApiReaderSettings? settings = null) where T : IOpenApiElement
         {
             return _jsonReader.ReadFragment<T>(input, version, openApiDocument, out diagnostic, settings);
         }

src/Microsoft.OpenApi/Any/OpenApiAny.cs

@@ -12,21 +12,21 @@ namespace Microsoft.OpenApi.Any
     /// </summary>
     public class OpenApiAny : IOpenApiElement, IOpenApiExtension
     {
-        private readonly JsonNode jsonNode;
+        private readonly JsonNode? jsonNode;
 
         /// <summary>
         /// Initializes the <see cref="OpenApiAny"/> class.
         /// </summary>
         /// <param name="jsonNode"></param>
-        public OpenApiAny(JsonNode jsonNode)
+        public OpenApiAny(JsonNode? jsonNode)
         {
             this.jsonNode = jsonNode;
         }
 
         /// <summary>
         /// Gets the underlying JsonNode.
         /// </summary>
-        public JsonNode Node { get { return jsonNode; } }
+        public JsonNode? Node { get { return jsonNode; } }
 
         /// <summary>
         /// Writes out the OpenApiAny type.

src/Microsoft.OpenApi/Attributes/DisplayAttribute.cs

@@ -15,14 +15,14 @@ public class DisplayAttribute : Attribute
         /// Initializes a new instance of the <see cref="DisplayAttribute"/> class.
         /// </summary>
         /// <param name="name">The display name.</param>
-        public DisplayAttribute(string name)
+        public DisplayAttribute(string? name)
         {
             Name = Utils.CheckArgumentNullOrEmpty(name);
         }
 
         /// <summary>
         /// The display Name.
         /// </summary>
-        public string Name { get; }
+        public string? Name { get; }
     }
 }

src/Microsoft.OpenApi/Exceptions/OpenApiException.cs

@@ -33,7 +33,7 @@ public OpenApiException(string message)
         /// </summary>
         /// <param name="message">The plain text error message for this exception.</param>
         /// <param name="innerException">The inner exception that is the cause of this exception to be thrown.</param>
-        public OpenApiException(string message, Exception innerException)
+        public OpenApiException(string message, Exception? innerException)
             : base(message, innerException)
         {
         }
@@ -46,6 +46,6 @@ public OpenApiException(string message, Exception innerException)
         /// a text/plain pointer as defined in https://tools.ietf.org/html/rfc5147
         /// Currently only line= is provided because using char= causes tests to break due to CR/LF and LF differences
         /// </summary>
-        public string Pointer { get; set; }
+        public string? Pointer { get; set; }
     }
 }

src/Microsoft.OpenApi/Exceptions/OpenApiReaderException.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;
@@ -39,7 +39,7 @@ public OpenApiReaderException(string message, ParsingContext context) : base(mes
         /// </summary>
         /// <param name="message">Plain text error message for this exception.</param>
         /// <param name="node">Parsing node where error occured</param>
-        public OpenApiReaderException(string message, JsonNode node) : base(message)
+        public OpenApiReaderException(string message, JsonNode? node) : base(message)
         {
             // This only includes line because using a char range causes tests to break due to CR/LF & LF differences
             // See https://tools.ietf.org/html/rfc5147 for syntax

src/Microsoft.OpenApi/Exceptions/OpenApiUnsupportedSpecVersionException.cs

@@ -18,7 +18,7 @@ public class OpenApiUnsupportedSpecVersionException : Exception
         /// Initializes the <see cref="OpenApiUnsupportedSpecVersionException"/> class with a specification version.
         /// </summary>
         /// <param name="specificationVersion">Version that caused this exception to be thrown.</param>
-        public OpenApiUnsupportedSpecVersionException(string specificationVersion)
+        public OpenApiUnsupportedSpecVersionException(string? specificationVersion)
             : base(string.Format(CultureInfo.InvariantCulture, messagePattern, specificationVersion))
         {
             this.SpecificationVersion = specificationVersion;
@@ -39,6 +39,6 @@ public OpenApiUnsupportedSpecVersionException(string specificationVersion, Excep
         /// <summary>
         /// The unsupported specification version.
         /// </summary>
-        public string SpecificationVersion { get; }
+        public string? SpecificationVersion { get; }
     }
 }

src/Microsoft.OpenApi/Exceptions/OpenApiWriterException.cs

@@ -33,7 +33,7 @@ public OpenApiWriterException(string message)
         /// </summary>
         /// <param name="message">The plain text error message for this exception.</param>
         /// <param name="innerException">The inner exception that is the cause of this exception to be thrown.</param>
-        public OpenApiWriterException(string message, Exception innerException)
+        public OpenApiWriterException(string message, Exception? innerException)
             : base(message, innerException)
         {
         }

src/Microsoft.OpenApi/Expressions/BodyExpression.cs

@@ -30,7 +30,7 @@ public BodyExpression()
         /// Initializes a new instance of the <see cref="BodyExpression"/> class.
         /// </summary>
         /// <param name="pointer">a JSON Pointer [RFC 6901](https://tools.ietf.org/html/rfc6901).</param>
-        public BodyExpression(JsonPointer pointer)
+        public BodyExpression(JsonPointer? pointer)
             : base(pointer?.ToString())
         {
             Utils.CheckArgumentNull(pointer);
@@ -55,6 +55,6 @@ public override string Expression
         /// <summary>
         /// Gets the fragment string.
         /// </summary>
-        public string Fragment { get => Value; }
+        public string? Fragment { get => Value; }
     }
 }

src/Microsoft.OpenApi/Expressions/HeaderExpression.cs

@@ -31,6 +31,6 @@ public HeaderExpression(string token)
         /// <summary>
         /// Gets the token string.
         /// </summary>
-        public string Token { get => Value; }
+        public string? Token { get => Value; }
     }
 }

src/Microsoft.OpenApi/Expressions/PathExpression.cs

@@ -31,6 +31,6 @@ public PathExpression(string name)
         /// <summary>
         /// Gets the name string.
         /// </summary>
-        public string Name { get => Value; }
+        public string? Name { get => Value; }
     }
 }

src/Microsoft.OpenApi/Expressions/QueryExpression.cs

@@ -31,6 +31,6 @@ public QueryExpression(string name)
         /// <summary>
         /// Gets the name string.
         /// </summary>
-        public string Name { get => Value; }
+        public string? Name { get => Value; }
     }
 }

src/Microsoft.OpenApi/Expressions/RuntimeExpression.cs

@@ -84,15 +84,15 @@ public override int GetHashCode()
         /// <summary>
         /// Equals implementation for IEquatable.
         /// </summary>
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return Equals(obj as RuntimeExpression);
         }
 
         /// <summary>
         /// Equals implementation for object of the same type.
         /// </summary>
-        public bool Equals(RuntimeExpression obj)
+        public bool Equals(RuntimeExpression? obj)
         {
             return obj != null && obj.Expression == Expression;
         }