@Override public V apply(AsyncResultSet input) {
    return map(input); // dispatched to Function so that toString is nicer vs a lambda
  }
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