Fix call base template

Author: genusP

src/ApiCodeGenerator.OpenApi/DefaultTemplateFactory.cs

@@ -58,12 +58,8 @@ public ITemplate CreateTemplate(string language, string template, object model)
         {
             if (model is Fluid.TemplateContext templateContext)
             {
-                var currentTemplate = (string)templateContext.AmbientValues["__template"];
+                var currentTemplate = ((string)templateContext.AmbientValues["__template"]).TrimEnd('!');
                 template = template.Substring(0, template.Length - BASE_TMPL_SUFFIX.Length);
-                if (!template.EndsWith("!"))
-                {
-                    template += "!";
-                }
 
                 providers = providers.SkipWhile(p => currentTemplate != p.GetFullName(template, language)).Skip(1);
             }

test/ApiCodeGenerator.OpenApi.Tests/DefaultTemplateFactoryTests.cs

@@ -51,7 +51,7 @@ public TestTemplateProvider(string templateText)
 
         public string? GetFullName(string name, string language)
         {
-            return name == "Class" || name == "Class!"
+            return name == "Class"
                 ? $"{_providerKey}.{name}"
                 : null;
         }