Used StringBuilder.Append(char) for single character strings (#9032)

Author: glen-84

.editorconfig

@@ -183,6 +183,8 @@ dotnet_diagnostic.CA1513.severity = warning
 # Do not initialize unnecessarily.
 dotnet_diagnostic.CA1805.severity = warning
 dotnet_diagnostic.RCS1129.severity = none
+# Use StringBuilder.Append(char) for single character strings.
+dotnet_diagnostic.CA1834.severity = warning
 # Simplify name.
 dotnet_diagnostic.IDE0001.severity = warning
 # Simplify member access.

src/HotChocolate/Adapters/src/Adapters.OpenApi.Core/Parser/OpenApiDefinitionParser.cs

@@ -182,7 +182,7 @@ private static (string Route, List<OpenApiEndpointDefinitionParameter> Parameter
 
         foreach (var segment in stringValue.Split('/', StringSplitOptions.RemoveEmptyEntries))
         {
-            routeBuilder.Append("/");
+            routeBuilder.Append('/');
 
             if (segment.StartsWith("{") && segment.EndsWith("}"))
             {

src/HotChocolate/AspNetCore/test/AspNetCore.Tests.Utilities/ClientQueryRequest.cs

@@ -35,7 +35,7 @@ public override string ToString()
         {
             if (Id is not null)
             {
-                query.Append("&");
+                query.Append('&');
             }
             query.Append($"query={Query.Replace("\r", "").Replace("\n", "")}");
         }

src/HotChocolate/Core/src/Authorization/AuthorizeDirective.cs

@@ -99,7 +99,7 @@ private static string BuildCacheKey(string? policy, IReadOnlyList<string>? roles
             sb.Append(policy);
         }
 
-        sb.Append(";");
+        sb.Append(';');
 
         if (roles is not null)
         {
@@ -109,7 +109,7 @@ private static string BuildCacheKey(string? policy, IReadOnlyList<string>? roles
 
                 if (i < roles.Count - 1)
                 {
-                    sb.Append(",");
+                    sb.Append(',');
                 }
             }
         }