public class EligibilityRequest {

 private String channel; // it's part of Equals
 ...

 private Lista<String> productCodes // it's not part of Equals and need to be aggregated within instance of EligibilityRequest "equal"

Map<EligibilityRequest, List<String>> uniqueEligibilityRequests = new HashMap<>();

  uniqueEligibilityRequests = requests.stream()
            .collect(groupingBy(request -> request,
                    Collectors.mapping(request -> request.getProductsCode(), toList())
                    ));