@Override
    public ListPartitionReassignmentsResult listPartitionReassignments(Optional<Set<TopicPartition>> partitions,
                                                                       ListPartitionReassignmentsOptions options) {
        final KafkaFutureImpl<Map<TopicPartition, PartitionReassignment>> partitionReassignmentsFuture = new KafkaFutureImpl<>();
        if (partitions.isPresent()) {
            for (TopicPartition tp : partitions.get()) {
                String topic = tp.topic();
                int partition = tp.partition();
                if (topicNameIsUnrepresentable(topic)) {
                    partitionReassignmentsFuture.completeExceptionally(new InvalidTopicException("The given topic name '"
                            + topic + "' cannot be represented in a request."));
                } else if (partition < 0) {
                    partitionReassignmentsFuture.completeExceptionally(new InvalidTopicException("The given partition index " +
                            partition + " is not valid."));
                }
                if (partitionReassignmentsFuture.isCompletedExceptionally())
                    return new ListPartitionReassignmentsResult(partitionReassignmentsFuture);
            }
        }
        final long now = time.milliseconds();
        runnable.call(new Call("listPartitionReassignments", calcDeadlineMs(now, options.timeoutMs()),
            new ControllerNodeProvider()) {

            @Override
            ListPartitionReassignmentsRequest.Builder createRequest(int timeoutMs) {
                ListPartitionReassignmentsRequestData listData = new ListPartitionReassignmentsRequestData();
                listData.setTimeoutMs(timeoutMs);

                if (partitions.isPresent()) {
                    Map<String, ListPartitionReassignmentsTopics> reassignmentTopicByTopicName = new HashMap<>();

                    for (TopicPartition tp : partitions.get()) {
                        if (!reassignmentTopicByTopicName.containsKey(tp.topic()))
                            reassignmentTopicByTopicName.put(tp.topic(), new ListPartitionReassignmentsTopics().setName(tp.topic()));

                        reassignmentTopicByTopicName.get(tp.topic()).partitionIndexes().add(tp.partition());
                    }

                    listData.setTopics(new ArrayList<>(reassignmentTopicByTopicName.values()));
                }
                return new ListPartitionReassignmentsRequest.Builder(listData);
            }

            @Override
            void handleResponse(AbstractResponse abstractResponse) {
                ListPartitionReassignmentsResponse response = (ListPartitionReassignmentsResponse) abstractResponse;
                Errors error = Errors.forCode(response.data().errorCode());
                switch (error) {
                    case NONE:
                        break;
                    case NOT_CONTROLLER:
                        handleNotControllerError(error);
                        break;
                    default:
                        partitionReassignmentsFuture.completeExceptionally(new ApiError(error, response.data().errorMessage()).exception());
                        break;
                }
                Map<TopicPartition, PartitionReassignment> reassignmentMap = new HashMap<>();

                for (OngoingTopicReassignment topicReassignment : response.data().topics()) {
                    String topicName = topicReassignment.name();
                    for (OngoingPartitionReassignment partitionReassignment : topicReassignment.partitions()) {
                        reassignmentMap.put(
                            new TopicPartition(topicName, partitionReassignment.partitionIndex()),
                            new PartitionReassignment(partitionReassignment.replicas(), partitionReassignment.addingReplicas(), partitionReassignment.removingReplicas())
                        );
                    }
                }

                partitionReassignmentsFuture.complete(reassignmentMap);
            }

            @Override
            void handleFailure(Throwable throwable) {
                partitionReassignmentsFuture.completeExceptionally(throwable);
            }
        }, now);

        return new ListPartitionReassignmentsResult(partitionReassignmentsFuture);
    }
Fail futures in the given Map which were retried due to exceeding quota. We propagate
the initial error back to the caller if the request timed out.
clients/src/main/java/org/apache/kafka/clients/admin/KafkaAdminClient.java