Using callActivity to create a subProcess, in the act_hi_procinst table, the subProcess's START_USER_ID_ is null, how to set a stater?

[Nan_Infinite]

in the act_hi_procinst, the BUSINESS_KEY_ is also null, and I using the following code to set a value for it.

execution.setProcessBusinessKey(bpmnStartData.getBusinessKey());

so , is there a interface to set the START_USER_ID_ for a subProcess

[Nan_Infinite]

I got the solution.
Just in the start event of callActivity, use the code blow

identityService.setAuthenticatedUserId("userId");