* use `get(key) ?: defaultValue` instead of this method, anyway.
     */
    V result = get(key);
    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
    if (result != null) {
      return result;
    } else {
      return defaultValue;
    }
  }

   * Returns a new ordering on {@code F} which orders elements by first applying a function to them,
   * then comparing those results using {@code this}. For example, to compare objects by their
   * string forms, in a case-insensitive manner, use:
   *
   * <pre>{@code
   * Ordering.from(String.CASE_INSENSITIVE_ORDER)
   *     .onResultOf(Functions.toStringFunction())
   * }</pre>
   *

     *
     * (Currently it's safe to pass instances for which compareTo() always
     * returns 0, but if we had a SingletonImmutableSortedSet, this might no
     * longer be the case.)
     *
     * javax.naming.Name and java.util.concurrent.Delayed might work, but
     * they're fairly obscure, we've invented our own interface and class.
     */
    Interface a = new Impl();

   * SoftReference} (by default, strong references are used). Softly-referenced objects will be
   * garbage-collected in a <i>globally</i> least-recently-used manner, in response to memory
   * demand.
   *
   * <p><b>Warning:</b> in most circumstances it is better to set a per-cache {@linkplain