PHP Notice when adding premiums to contribution pages and more generally when using Rest client requests to CRM_Financial_Page_Ajax.php

The CiviCRM Financial component defines its REST functions in the page CRM_Financial_Page_Ajax.php.

These functions are then invoked through:
return call_user_func(array($params['className'], $params['fnName']), $params);

https://github.com/civicrm/civicrm-core/blob/master/CRM/Utils/REST.php#L331

This syntax assumes that the functions of the Ajax.php pages are static but most are not static even in the core file. Therefore we receive a notice:
"Strict warning: call_user_func() expects parameter 1 to be a valid callback, non-static method CRM_Financial_Page_AJAX::jqFinancialType() should not be called statically in CRM_Utils_REST::process() (line 329 of /var/www/myhost/sites/all/modules/civicrm/CRM/Utils/REST.php)."

It looks like the syntax should either be changed or the methods such as jqFinancialType should be declared static.

$class = new $params['className'];
return call_user_func(array($class, $params['fnName']), $params);

http://stackoverflow.com/questions/273169/how-do-i-dynamically-invoke-a-class-method-in-php/273176#273176