Response/Params

* so we can't directly use BackedEnum::tryFrom as validator, because if
   the Enum is of <int> and the string is not what php considers numeric,
   we get a straight TypeError Exception instead of null for failing the tryFrom.

includes/components/response/baseresponse.class.php

@@ -645,6 +645,13 @@ abstract class BaseResponse
         return preg_replace('/ +/', ' ', trim($str));
     }
 
+    protected static function checkLocale(string $localeId) : ?Locale
+    {
+        if (Util::checkNumeric($localeId, NUM_CAST_INT))
+            return Locale::tryFrom($localeId);
+        return null;
+    }
+
 
     /********************/
     /* child implements */