diff --git a/src/templates/core/OpenAPI.hbs b/src/templates/core/OpenAPI.hbs
index 19e66fbf..7b9560a2 100644
--- a/src/templates/core/OpenAPI.hbs
+++ b/src/templates/core/OpenAPI.hbs
@@ -10,11 +10,11 @@ export type OpenAPIConfig = {
 	VERSION: string;
 	WITH_CREDENTIALS: boolean;
 	CREDENTIALS: 'include' | 'omit' | 'same-origin';
-	TOKEN?: string | Resolver<string>;
-	USERNAME?: string | Resolver<string>;
-	PASSWORD?: string | Resolver<string>;
-	HEADERS?: Headers | Resolver<Headers>;
-	ENCODE_PATH?: (path: string) => string;
+	TOKEN?: string | Resolver<string> | undefined;
+	USERNAME?: string | Resolver<string> | undefined;
+	PASSWORD?: string | Resolver<string> | undefined;
+	HEADERS?: Headers | Resolver<Headers> | undefined;
+	ENCODE_PATH?: ((path: string) => string) | undefined;
 };
 
 export const OpenAPI: OpenAPIConfig = {