@Override protected final boolean doIsCanceled() {
    CompletableFuture<V> maybeFuture = future;
    return maybeFuture != null && maybeFuture.isCancelled();
  }
Defers I/O until {@link #enqueue(Callback)} or {@link #execute()} are called.
zipkin-storage/cassandra/src/main/java/zipkin2/storage/cassandra/internal/call/ResultSetFutureCall.java