Milestone::find incorrect arguments

[cmbirk]

I'm trying to make the following call with included exception:

Teamwork::project($projectId)->milestones($id)->find(['getProgress' => 'true', 'showTaskLists' => 'true', 'showTasks' => 'true']);

and getting the exception

exception 'ErrorException' with message 'array_key_exists() expects parameter 2 to be array, integer given' in .../vendor/rossedman/teamwork/src/Rossedman/Teamwork/AbstractObject.php:61