@Override
    public T get() throws InterruptedException, ExecutionException {
        try {
            return completableFuture.get();
        } catch (ExecutionException e) {
            maybeThrowCancellationException(e.getCause());
            throw e;
        }
    }
Waits if necessary for this future to complete, and then returns its result.
clients/src/main/java/org/apache/kafka/common/internals/KafkaFutureImpl.java