@Override
            public LeastLoadedNode leastLoadedNode(long now) {
                for (Node node : metadata.fetch().nodes()) {
                    if (isReady(node, now) && canSendMore)
                        return new LeastLoadedNode(node, true);
                }
                return new LeastLoadedNode(null, false);
            }
It creates response with new leader info and new nodes, as stated in KIP-951
clients/src/test/java/org/apache/kafka/clients/producer/internals/SenderTest.java