private <T> List<Future<T>> submitAll(ExecutorService executor,
        Collection<? extends Callable<T>> tasks) {
      List<Future<T>> result = new ArrayList<>(tasks.size());

      for (Callable<T> task : tasks) {
        result.add(executor.submit(task));
      }

      return result;
    }
This gets pending requests and returns the IDs of any that are in the given collection

@param mbrs collection of IDs to search for
@param matchingMembers collection to store matching IDs in
@param requestType leave/remove/join
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/membership/GMSJoinLeave.java