}

  @Override
  @CheckForNull
  public K ceilingKey(@ParametricNullness K key) {
    return delegate().ceilingKey(key);
  }

  /**
   * A sensible definition of {@link #ceilingKey} in terms of {@code ceilingEntry}. If you override
   * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
   * implementation.
   */
  @CheckForNull

  }

  @Override
  @CheckForNull
  public K ceilingKey(@ParametricNullness K key) {
    return delegate().ceilingKey(key);
  }

  /**
   * A sensible definition of {@link #ceilingKey} in terms of {@code ceilingEntry}. If you override
   * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
   * implementation.
   */
  @CheckForNull