remove redundant casts

src/Microsoft.OpenApi.Readers/OpenApiStreamReader.cs

@@ -60,9 +60,9 @@ public OpenApiDocument Read(Stream input, out OpenApiDiagnostic diagnostic)
         public async Task<ReadResult> ReadAsync(Stream input, CancellationToken cancellationToken = default)
         {
             MemoryStream bufferedStream;
-            if (input is MemoryStream)
+            if (input is MemoryStream stream)
             {
-                bufferedStream = (MemoryStream)input;
+                bufferedStream = stream;
             }
             else
             {

src/Microsoft.OpenApi.Readers/ParseNodes/OpenApiAnyConverter.cs

@@ -50,16 +50,16 @@ public static IOpenApiAny GetSpecificOpenApiAny(IOpenApiAny openApiAny, OpenApiS
                 return newObject;
             }
 
-            if (!(openApiAny is OpenApiString))
+            if (openApiAny is not OpenApiString apiString)
             {
                 return openApiAny;
             }
 
-            var value = ((OpenApiString)openApiAny).Value;
+            var value = apiString.Value;
             var type = schema?.Type;
             var format = schema?.Format;
 
-            if (((OpenApiString)openApiAny).IsExplicit())
+            if (apiString.IsExplicit())
             {
                 // More narrow type detection for explicit strings, only check types that are passed as strings
                 if (schema == null)
@@ -113,7 +113,7 @@ public static IOpenApiAny GetSpecificOpenApiAny(IOpenApiAny openApiAny, OpenApiS
                     }
                 }
 
-                return openApiAny;
+                return apiString;
             }
 
             if (value is null or "null")
@@ -247,7 +247,7 @@ public static IOpenApiAny GetSpecificOpenApiAny(IOpenApiAny openApiAny, OpenApiS
 
                 if (type == "string")
                 {
-                    return openApiAny;
+                    return apiString;
                 }
 
                 if (type == "boolean")
@@ -262,7 +262,7 @@ public static IOpenApiAny GetSpecificOpenApiAny(IOpenApiAny openApiAny, OpenApiS
             // If data conflicts with the given type, return a string.
             // This converter is used in the parser, so it does not perform any validations, 
             // but the validator can be used to validate whether the data and given type conflicts.
-            return openApiAny;
+            return apiString;
         }
     }
 }

src/Microsoft.OpenApi/Extensions/OpenAPIWriterExtensions.cs

@@ -16,9 +16,9 @@ internal static class OpenAPIWriterExtensions
         /// <returns></returns>
         internal static OpenApiWriterSettings GetSettings(this IOpenApiWriter openApiWriter) 
         {
-            if (openApiWriter is OpenApiWriterBase)
+            if (openApiWriter is OpenApiWriterBase @base)
             {
-                return ((OpenApiWriterBase)openApiWriter).Settings;
+                return @base.Settings;
             }
             return new OpenApiWriterSettings();
         }

src/Microsoft.OpenApi/Models/OpenApiParameter.cs

@@ -411,10 +411,10 @@ public void SerializeAsV2WithoutReference(IOpenApiWriter writer)
         {
             Style = In switch
             {
-                ParameterLocation.Query => (ParameterStyle?)ParameterStyle.Form,
-                ParameterLocation.Header => (ParameterStyle?)ParameterStyle.Simple,
-                ParameterLocation.Path => (ParameterStyle?)ParameterStyle.Simple,
-                ParameterLocation.Cookie => (ParameterStyle?)ParameterStyle.Form,
+                ParameterLocation.Query => ParameterStyle.Form,
+                ParameterLocation.Header => ParameterStyle.Simple,
+                ParameterLocation.Path => ParameterStyle.Simple,
+                ParameterLocation.Cookie => ParameterStyle.Form,
                 _ => (ParameterStyle?)ParameterStyle.Simple,
             };
 

src/Microsoft.OpenApi/Validations/Rules/RuleHelpers.cs

@@ -75,16 +75,14 @@ public static void ValidateDataTypeMismatch(
                 }
 
                 // If value is not a string and also not an object, there is a data mismatch.
-                if (!(value is OpenApiObject))
+                if (value is not OpenApiObject anyObject)
                 {
                     context.CreateWarning(
                         ruleName,
                         DataTypeMismatchedErrorMessage);
                     return;
                 }
 
-                var anyObject = (OpenApiObject)value;
-
                 foreach (var key in anyObject.Keys)
                 {
                     context.Enter(key);
@@ -115,16 +113,14 @@ public static void ValidateDataTypeMismatch(
                 }
 
                 // If value is not a string and also not an array, there is a data mismatch.
-                if (!(value is OpenApiArray))
+                if (value is not OpenApiArray anyArray)
                 {
                     context.CreateWarning(
                         ruleName,
                         DataTypeMismatchedErrorMessage);
                     return;
                 }
 
-                var anyArray = (OpenApiArray)value;
-
                 for (int i = 0; i < anyArray.Count; i++)
                 {
                     context.Enter(i.ToString());