How to stop supervisory hierarchy approvals when it reaches at a maximum job level or job

Summary:

Hello, 

The customer wants supervisory approval hierarchy to be routed until the job level 5 if the requisition amount is greater than 25k USD. 

I would like to learn the query that i need to insert into "Top Participant" field in BPM as a condition which returns the name of the employee whose job level is 5 in the supervisory hierarchy. 

I wrote the following condition: HierarchyBuilder.getManager("supervisory",HierarchyPrincipal.jobLevel==5,-1,"",""). However, when i validate the condition, I see the below warning message : 

RUL-05721: The result type of the expression is "boolean" but should be "String". 

Could you please let me know how this can be solved ?