how do i retrieve the person who has started a process in version 7.1?

In version 5, i used this code to retrieve the person who started the process.
processInstance.getStartedBy()

In version 7, i used the same code :processInstanceId.getStartedBy().
Bu it gives me an error.Some problem with the return type .
Return type is long and not string i guess.

Is there any other way to retrieve who started the process?

Regards
A.

You can use a following script:
apiAccessor.processAPI.getProcessInstance(processInstanceId).startedBy