Show all rows when Data Source Parameter is empty

I have a data source parameter that works fine, except, when the parameter is empty, it shows no rows. I want it to show all rows by default.

Here is an example how to set this up for parameter [Recruiter Parm]:

select * from EXAMPLES.COMMERCE.ALLSUMMARY 
 where 
 	CASE 
 		WHEN {{Recruiter Parm}} IS NULL OR TRIM({{Recruiter Parm}})='' THEN True  // if input parameter is blank, return all rows. Without this, blank parameter could lead to 0 row output
 		ELSE PRIMARYRECRUITER ILIKE '%' || TRIM({{Recruiter Parm}}) || '%'        // case insensitive parameter by using ILIKE
 	END