Fix sonarcloud issues

Author: mganss

XmlSchemaClassGenerator/FileOutputWriter.cs

@@ -98,5 +98,5 @@ private void WriteSeparateFiles(CodeNamespace cn)
 
     static readonly Regex InvalidCharacters = new($"[{string.Join("", Path.GetInvalidFileNameChars())}]", RegexOptions.Compiled);
 
-    private string ValidateName(string name) => InvalidCharacters.Replace(name, "_");
+    private static string ValidateName(string name) => InvalidCharacters.Replace(name, "_");
 }

XmlSchemaClassGenerator/ModelBuilder.cs

@@ -24,7 +24,7 @@ internal class ModelBuilder
 
     private static readonly XmlQualifiedName AnyType = new("anyType", XmlSchema.Namespace);
 
-    private string BuildKey(XmlSchemaAnnotated annotated, XmlQualifiedName name)
+    private static string BuildKey(XmlSchemaAnnotated annotated, XmlQualifiedName name)
         => $"{annotated.GetType()}:{annotated.SourceUri}:{annotated.LineNumber}:{annotated.LinePosition}:{name}";
 
     private void SetType(XmlSchemaAnnotated annotated, XmlQualifiedName name, TypeModel type)

XmlSchemaClassGenerator/TypeModel.cs

@@ -28,7 +28,7 @@ public static CodeNamespace Generate(string namespaceName, IEnumerable<Namespace
     {
         var codeNamespace = new CodeNamespace(namespaceName);
 
-        foreach (var (Namespace, Condition) in CodeUtilities.UsingNamespaces.Where(n => n.Condition(conf)).OrderBy(n => n.Namespace))
+        foreach (var (Namespace, _) in CodeUtilities.UsingNamespaces.Where(n => n.Condition(conf)).OrderBy(n => n.Namespace))
             codeNamespace.Imports.Add(new CodeNamespaceImport(Namespace));
 
         foreach (var typeModel in parts.SelectMany(x => x.Types.Values).ToList())