* - keys: mixed; array of string, eg array("com.example.myextension1", "com.example.myextension2") or string with comma-delimited list
* using 'keys' should be more performant than making multiple API calls with 'key'
*
* - keys: mixed; array of string, eg array("com.example.myextension1", "com.example.myextension2") or string with comma-delimited list
* using 'keys' should be more performant than making multiple API calls with 'key'
*