strlen() expects parameter 1 to be string, array given

[wslsq]

php版本：8.1.17
clinet版本：v3.0.14

代码
$roomIds = [ 2, 3, 4 ];
Gateway::joinGroup(xxxxxxxxxx, $roomIds);

报错
local.ERROR: strlen(): Argument #1 ($string) must be of type string, array given {"exception":"[object] (TypeError(code: 0): strlen(): Argument #1 ($string) must be of type string, array given at D:\laragon\www\da-back\vendor\workerman\gatewayclient\Gateway.php:1579)
[stacktrace]

1579行代码
$ext_len = strlen($data['ext_data']);

断点$data输出
array (
'cmd' => 20,
'local_ip' => 0,
'local_port' => 0,
'client_ip' => 0,
'client_port' => 0,
'connection_id' => 487,
'flag' => 1,
'gateway_port' => 0,
'ext_data' =>
array (
0 => 2,
1 => 3,
2 => 4,
),
'body' => '',
)

[wslsq]

对不起，看错了，以为可以批量入群