How to pass Business Key to Call Activity

Flowable Designer
1

Hi,

How to pass businessKey from main process to multiple Call Activity which are getting call from the master process.

PROCESS_INSTANCE_ID will be unique for each call activity process.

2

You can map the business key as an input parameter into the call activity by mapping ${execution.processInstance.businessKey}

3

does this need to be set in Business key expression? under call activity?