@Override
    public ClientRequest newClientRequest(String nodeId,
                                          AbstractRequest.Builder<?> requestBuilder,
                                          long createdTimeMs,
                                          boolean expectResponse,
                                          int requestTimeoutMs,
                                          RequestCompletionHandler callback) {
        return new ClientRequest(nodeId, requestBuilder, nextCorrelationId(), clientId, createdTimeMs, expectResponse,
                requestTimeoutMs, callback);
    }
Add a metadata request to the list of sends if we can make one
clients/src/main/java/org/apache/kafka/clients/NetworkClient.java