Description
Currently, tagged locators using the default_index_method static method name pointer must point to a method whose return type is string. However, my objects expose integer keys. Rather than rewrite my application to fit Symfony (where string does not make sense to the application), I think it better that Symfony should accept integer keys and internally convert them to string if so needed.

Example

  MyService:
    arguments:
      $foo: !tagged_locator
        tag: my_tag
        default_index_method: myStaticMethod # returns integer