// Returning successfully is not ideal, but tolerated.
      } catch (NullPointerException tolerated) {
      }
    } else {
      try {
        entrySet.retainAll(null);
        // We have to tolerate a successful return (Sun bug 4802647)
      } catch (UnsupportedOperationException | NullPointerException e) {
        // Expected.
      }
    }
    assertInvariants(map);
  }

     *
     * TODO(cpovirk): decide what the best long-term action here is: force users
     * to suppress (as we do now), stop testing entrySet().add() at all, make
     * entrySet().add() tests tolerant of either behavior, introduce a map
     * feature for entrySet() that supports add(), or something else
     */
    return asList(
        getAddUnsupportedNotPresentMethod(),

   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class
   * include testing that {@code equals()} is reflexive and is tolerant of {@code null}. However,
   * there's no problem. The reason: {@link EqualsTester} tests {@code null} and identical inputs
   * directly against {@code equals()} rather than through the {@code Equivalence}.
   */

  }

  /*
   * Our implementation works fine with a null `dir`. However, there's nothing in the documentation
   * of the supertype that suggests that implementations are expected to tolerate null. That said, I
   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if

     *
     * TODO(cpovirk): decide what the best long-term action here is: force users
     * to suppress (as we do now), stop testing entrySet().add() at all, make
     * entrySet().add() tests tolerant of either behavior, introduce a map
     * feature for entrySet() that supports add(), or something else
     */
    return asList(
        getAddUnsupportedNotPresentMethod(),

   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class
   * include testing that {@code equals()} is reflexive and is tolerant of {@code null}. However,
   * there's no problem. The reason: {@link EqualsTester} tests {@code null} and identical inputs
   * directly against {@code equals()} rather than through the {@code Equivalence}.
   */

gender identity or expression, language, national origin, political beliefs, profession, race,
religion, sexual orientation, socioeconomic status, and technical ability. We will not tolerate
discrimination based on any of the protected characteristics above, including participants with
disabilities.

Reporting Issues
----------------

/** Delete file we expect but don't require to exist. */
internal fun FileSystem.deleteIfExists(path: Path) {
  try {
    delete(path)
  } catch (fnfe: FileNotFoundException) {
    return
  }
}

/** Tolerant delete, try to clear as many files as possible even after a failure. */
internal fun FileSystem.deleteContents(directory: Path) {
  var exception: IOException? = null
  val files =
    try {
      list(directory)

   * null}).
   *
   * <p>The list of results is in the same order as the input list.
   *
   * <p>This differs from {@link #allAsList(ListenableFuture[])} in that it's tolerant of failed
   * futures for any of the items, representing them as {@code null} in the result list.
   *
   * <p>Canceling this future will attempt to cancel all the component futures.
   *

 *
 * Clients call [get] to read a snapshot of an entry. The read will observe the value at the time
 * that [get] was called. Updates and removals after the call do not impact ongoing reads.
 *
 * This class is tolerant of some I/O errors. If files are missing from the filesystem, the
 * corresponding entries will be dropped from the cache. If an error occurs while writing a cache