run the same test multiple times with gradle

multipleTestExecution

class LoadTest extends Test{
	private numberOfClients = 2
	
	public LoadTest(){
		super()
	}
	public FileTree getCandidateClassFiles() {
		FileTree candidateTimes = super.getCandidateClassFiles()
		for(int client  = 1; client<numberOfClients;client++){
			candidateTimes = candidateTimes + super.getCandidateClassFiles()
		}
		return candidateTimes
	}
	
}

task loadTest(type:LoadTest){
}

This doesn't work, at least with Gradle 4.7 it does not, because adding the same file to a FileTree is not doing anything, because a FileTree behaves like a Set, eliminating duplicates.