CompletableFuture with different return type

Question

I have to make rest api calls to different Downstream systems and done coding like below,

Class Investorservice {
  public **Boolean** service1(String id){
     Boolean status = call downstream with id and return the status
     return status;
   }

  public **Boolean** service2(String id){
     Boolean status = call downstream with id and return status
     return status;
   }

   public **InputStream** service3(String id){
      InputStream is = call downstream to get IS;
     return is;
   }

   public **Boolean** service4(InputStream is){
     Boolean status =// Pass the input stream to external system with rest api
     return status;
   }
}

---

public class RestClientController {

Investorservice obj;
public void rest service( @RequestParam String id){
// listfuture contains service 1&2 call which makes third party call, do some processing and return the status
List<CompletableFuture<Boolean>>listFuture = new ArrayList();
 listFuture.add(obj.service1(id));
 listFuture.add(obj.service2(id));

CompletableFuture<Void> allFuture = CompletableFuture.allOf(listFuture.toArray(new CompletableFuture[listFuture.size()]));
CompletableFuture<List<Boolean>> allCompFuture = allFuture.thenApply(future -> listFuture.stream()
 .map(CompletableFuture::join).collect(Collectors.toList()));

List<Boolean> resultFuture= allCompFuture.get();


// How can I add service 3 call to listFuture as it's different return type adding serice3 gives compilation error.
// Then based on service 1&2 response in resultFuture(i.e if both are successful), I need to invoke Service 4 with output of Service 3
 }
}

Now I'm stuck at adding service3 call to listFuture and invoking Service 4 on success of Service 1&2.

 listFuture.add(obj.service3(id), executors); // giving compilation error due to different return type

1. How can I add service3 to listFuture and run Service 1, 2 & 3 all in parallel?

2. On Successful response for service1 and service2 (i.e both service response should be true), How can I collect and pass the Service3 output to Service 4 and make service4 call?