Hello,
There seams to be a problem and I'm unable to trace it:
Supervisord version 3.3.1
#php api output
API Version: 3.0
ApiClients\Client\Supervisord\Resource\Sync\State
statecode: 1
statename: RUNNING
log cleared
Identification: supervisor
PID: 29894
$program = current($client->programs()); //Calling this gives the error

PHP Warning: Illegal string offset 'value' in /home/xxx/vendor/api-clients/xml-rpc-service/src/XmlRpcPayloadParser.php on line 42

PHP Notice: Uninitialized string offset: 0 in /home/xxx/vendor/api-clients/xml-rpc-service/src/XmlRpcPayloadParser.php on line 42

PHP Fatal error: Uncaught Rx\React\RejectedPromiseException: Promise rejected with non-exception in /home/xxx/vendor/reactivex/rxphp/src/React/Promise.php:88

Is there a versioning mismatch between the api and xml-rpc?
What can be done?
Thank you.

my supervisord config is setted username and password.
at you example have not authorized .
how can i authorized i api to access the supervisord.