Fix CodeQL warnings

Author: MaggieKimani1

src/Microsoft.OpenApi/Models/OpenApiDocument.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;

src/Microsoft.OpenApi/Models/OpenApiParameter.cs

@@ -204,14 +204,7 @@ public void SerializeAsV3(IOpenApiWriter writer)
         /// <returns>OpenApiParameter</returns>
         public OpenApiParameter GetEffective(OpenApiDocument doc)
         {
-            if (this.Reference != null)
-            {
-                return doc.ResolveReferenceTo<OpenApiParameter>(this.Reference);
-            }
-            else
-            {
-                return this;
-            }
+            return Reference != null ? doc.ResolveReferenceTo<OpenApiParameter>(Reference) : this;
         }
 
         /// <summary>

src/Microsoft.OpenApi/Models/OpenApiRequestBody.cs

@@ -96,14 +96,7 @@ public void SerializeAsV3(IOpenApiWriter writer)
         /// <returns>OpenApiRequestBody</returns>
         public OpenApiRequestBody GetEffective(OpenApiDocument doc)
         {
-            if (this.Reference != null)
-            {
-                return doc.ResolveReferenceTo<OpenApiRequestBody>(this.Reference);
-            }
-            else
-            {
-                return this;
-            }
+            return Reference != null ? doc.ResolveReferenceTo<OpenApiRequestBody>(Reference) : this;
         }
 
         /// <summary>
@@ -157,7 +150,7 @@ internal OpenApiBodyParameter ConvertToBodyParameter()
                 Required = Required,
                 Extensions = Extensions.ToDictionary(static k => k.Key, static v => v.Value)  // Clone extensions so we can remove the x-bodyName extensions from the output V2 model.
             };
-            if (bodyParameter.Extensions.ContainsKey(OpenApiConstants.BodyName))
+            if (bodyParameter.Extensions.TryGetValue(OpenApiConstants.BodyName, out var bodyParameterName))
             {
                 bodyParameter.Name = (Extensions[OpenApiConstants.BodyName] as OpenApiString)?.Value ?? "body";
                 bodyParameter.Extensions.Remove(OpenApiConstants.BodyName);

src/Microsoft.OpenApi/Models/OpenApiResponse.cs

@@ -101,14 +101,7 @@ public void SerializeAsV3(IOpenApiWriter writer)
         /// <returns>OpenApiResponse</returns>
         public OpenApiResponse GetEffective(OpenApiDocument doc)
         {
-            if (this.Reference != null)
-            {
-                return doc.ResolveReferenceTo<OpenApiResponse>(this.Reference);
-            }
-            else
-            {
-                return this;
-            }
+            return Reference != null ? doc.ResolveReferenceTo<OpenApiResponse>(Reference) : this;
         }
 
         /// <summary>