We have the proper type as described in the external lib function descriptions. But external lib does not return values of the types described in the function descriptions. This is OK for PHP which is loosely typed but need some processing to correct types before serializing values and returning them to Flash via the amf web service.

In the patch attached to MDL-20808 I have added to the dynamically created service class calls to the external_api static function validate_parameters. This as well as validating the return value also casts it to the correct type.