* to {@code statusFuture} <i>in addition to</i> the call you make to {@link #finishToFuture()} or
   * a derivation method <i>on the same instance</i>. This is important because calling {@code
   * statusFuture} alone does not provide a way to close the pipeline.
   */
  public ListenableFuture<?> statusFuture() {
    return nonCancellationPropagating(future.transform(constant(null), directExecutor()));
  }

  /**

import javax.annotation.CheckForNull;

/**
 * {@link Table} implementation backed by a map that associates row keys with column key / value
 * secondary maps. This class provides rapid access to records by the row key alone or by both keys,
 * but not by just the column key.
 *
 * <p>The views returned by {@link #column}, {@link #columnKeySet()}, and {@link #columnMap()} have